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Source code

Simulate

OpenTerrace class.

Source code in openterrace/openterrace.py 
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class Simulate:
    """OpenTerrace class."""

    def __init__(self, t_start:float=0, t_end:float=None, dt:float=None):
        """Initialise with various control parameters.

        Args:
            t_start (float): Start time in s
            t_end (float): End time in s
            dt (float): Time step size in s
        """
        self.t_start = t_start
        self.t_end = t_end
        self.dt = dt
        self.coupling = []
        self.flag_coupling = False

    def create_phase(self, n:int=None, n_other:int=1, type:str=None):
        """Creates a fluid or bed phase.

        Args:
            n (int): Number of discretisations
            n_other (int): Number of discretisations of interacting phase. If you are defining a bed phase within a tank. Then n_other is the number of discretisations of the fluid phase.
            type (str): Phase type
        """

        valid_types = ['fluid','bed']
        if type not in valid_types:
            raise Exception("Type \'"+type+"\' specified. Valid options for types are:", valid_types)
        return self.Phase(self, n, n_other, type)

    def select_coupling(self, fluid_phase:int=None, bed_phase:int=None, h_exp:str=None, h_value:float=None):
        """Selects coupling of a fluid and bed phase

        Args:
            fluid_phase (int): phase number
            bed_phase (int): phase number
            h_exp (str): Predefined function for convective heat transfer
            h_value (float): Convective heat transfer coefficient in W/(m^2 K)
        """

        valid_h_exp = ['constant']
        if h_exp not in valid_h_exp:
            raise Exception("h_exp \'"+h_exp+"\' specified. Valid options for h_exp are:", valid_h_exp)

        self.coupling.append({"fluid_phase":fluid_phase, "bed_phase":bed_phase, "h_exp":h_exp, "h_value":h_value})
        self.flag_coupling = True

    def _coupling(self):
        """This is the function that couples the fluid and bed phase."""
        for couple in self.coupling:
            n_bed = self.Phase.instances[couple['fluid_phase']].domain.V/self.Phase.instances[couple['fluid_phase']].phi*(1-self.Phase.instances[couple['fluid_phase']].phi)/self.Phase.instances[couple['bed_phase']].domain.V0 #ok

            Q = couple['h_value']*self.Phase.instances[couple['bed_phase']].domain.A[-1][-1]*(self.Phase.instances[couple['fluid_phase']].T[0]-self.Phase.instances[couple['bed_phase']].T[:,-1])*self.dt #ok

            self.Phase.instances[couple['bed_phase']].h[:,-1] = self.Phase.instances[couple['bed_phase']].h[:,-1] + Q/(self.Phase.instances[couple['bed_phase']].rho[:,-1] * self.Phase.instances[couple['bed_phase']].domain.V[-1]) #ok

            self.Phase.instances[couple['fluid_phase']].h[0] = self.Phase.instances[couple['fluid_phase']].h[0] - n_bed * Q/(self.Phase.instances[couple['fluid_phase']].rho*self.Phase.instances[couple['fluid_phase']].domain.V) #ok

    def run_simulation(self):
        """If you want to run the simulation, you need to call this function. If data output is specified using the select_output function, the data will live in that specific phase instance. For more details on how to access the data, please refer to the tutorials."""


        for t in tqdm.tqdm(np.arange(self.t_start, self.t_end+self.dt, self.dt)):

            for phase_instance in self.Phase.instances:
                phase_instance._save_data(t)
                phase_instance._solve_equations(t, self.dt)
                phase_instance._update_properties()
            if self.flag_coupling:
                self._coupling()
    class Phase:
        instances = []
        """Main class to define either the fluid or bed phase."""

        def __init__(self, outer=None, n:int=None, n_other:int=None, type:str=None):
            """Initialise a phase with number of control points and type.

            Args:
                outer (object): Outer class
                n (int): Number of discretisations for the given phase
                n_other (int): Number of discretisations for the other phase
                type (str): Type of phase
            """

            self.outer = outer
            self.__class__.instances.append(self)
            self.n = n
            self.n_other = n_other

            self.phi = 1
            self.bcs = []
            self.sources = []

            self._flag_save_data = False
            self.type = type

        def select_substance_on_the_fly(self, cp:float=None, rho:float=None, k:float=None):
            """Defines and selects a new substance on-the-fly. This is useful for defining a substance for testing purposes with temperature independent properties.

            Args:
                cp (float): Specific heat capacity in J/(kg K)
                rho (float): Density in kg/m^3
                k (float): Thermal conductivity in W/(m K)
            """
            class dummy:
                pass
            self.fcns = dummy()
            self.fcns.h = lambda T: np.ones_like(T)*T*cp
            self.fcns.T = lambda h: np.ones_like(h)*h/cp
            self.fcns.cp = lambda h: np.ones_like(h)*cp
            self.fcns.k = lambda h: np.ones_like(h)*k
            self.fcns.rho = lambda h: np.ones_like(h)*rho

        def select_substance(self, substance:str=None):
            """Selects one of the predefined substancers.

            Args:
                substance (str): Substance name
            """

            valid_substances = globals()[self.type+'_substances'].__all__
            if not substance:
                raise Exception("Keyword 'substance' not specified.")
            if not substance in valid_substances:
                raise Exception(substance+" specified as "+self.type+" substance. Valid "+self.type+" substances are:", valid_substances)
            self.fcns = getattr(globals()[self.type+'_substances'], substance)

        def select_h_coeff(self, h_exp:str=None, value:float=None):
            """Selects an expression for the heat transfer coefficient.

            Args:
                h_exp (str): Heat transfer coefficient expression
                value (float): Heat transfer coefficient value
            """

            valid_correlations = ['constant']
            if correlation not in valid_correlations:
                raise Exception("correlation \'"+correlation+"\' specified. Valid options for correlation are:", valid_correlations)
            self.fcns.h_correlation = getattr(globals()['heat_transfer_correlations'], correlation)

        def select_domain_shape(self, domain:str=None, **kwargs):
            """Select domain shape and initialise constants.

            Args:
                domain (str): Domain type
                **kwargs (float): Dimensions of domain to be specified depnding on the domain type
            """

            if not domain:
                raise Exception("Keyword 'domain' not specified.")
            if not domain in globals()['domains'].__all__:
                raise Exception("domain \'"+domain+"\' specified. Valid options for domain are:", self.valid_domains)

            kwargs['n'] = self.n 
            self.domain = getattr(globals()['domains'], domain)
            self.domain.type = domain
            self.domain.validate_input(kwargs, domain)
            self.domain.shape = self.domain.shape(kwargs)
            self.domain.dx = self.domain.dx(kwargs)
            self.domain.A = self.domain.A(kwargs)
            self.domain.V = self.domain.V(kwargs)
            self.domain.V0 = self.domain.V0(kwargs)
            self.node_pos = self.domain.node_pos(kwargs)

        def select_porosity(self, phi:float=1):
            """Select porosity from 0 to 1, e.g. filling the domain with the phase up to a certain degree.

            Args:
                phi (float): Porosity value
            """

            self.domain.V = self.domain.V*phi
            self.phi = phi

        def select_schemes(self, diff:str=None, conv:str=None):
            """Imports the specified diffusion and convection schemes.

            Args:
                diff (str): Differenctial scheme
                conv (str): Convection scheme
            """

            if self.domain.type == 'lumped':
                raise Exception("'lumped' has been selected as domain type. Please don't specify a discretisation scheme.")

            if diff is not None:
                try:
                    self.diff = getattr(getattr(globals()['diffusion_schemes'], diff), diff)
                except:
                    raise Exception("Diffusion scheme \'"+diff+"\' specified. Valid options for diffusion schemes are:", diffusion_schemes.__all__)

            if conv is not None:
                try:
                    self.conv = getattr(getattr(globals()['convection_schemes'], conv), conv)
                except:
                    raise Exception("Convection scheme \'"+conv+"\' specified. Valid options for convection schemes are:", convection_schemes.__all__)

        def select_initial_conditions(self, T:list[float]=None):
            """Initialises temperature field.

            Args:
                T (float): List of length n with initial temperatures
            """

            if np.array(T).size == 1:
                self.T = np.tile(T,(np.append(self.n_other,self.domain.shape)))   
            elif np.array(T).size == self.n:
                self.T = np.tile(T,(np.append(self.n_other,1)))
            else: Exception("Length of T must be 1 or equal to n")

            self.h = self.fcns.h(self.T)
            self.T = self.fcns.T(self.h)
            self.rho = self.fcns.rho(self.h)
            self.cp = self.fcns.cp(self.h)
            self.k = self.fcns.k(self.h)
            self.D = np.zeros(((2,)+(self.T.shape)))
            self.F = np.zeros(((2,)+(self.T.shape)))
            self.S = np.zeros(self.T.shape)

        def select_massflow(self, mdot:list[float]=None):
            """Initialises mass flow rate field.

            Args:
                mdot (float): Array of mass flow rate. Column 0 is time and column 1 is mass flow rate
            """

            self.mdot_array = np.array(mdot)

        def select_bc(self, bc_type:str=None, parameter:str=None, position=None, value:float=None):
            """Specify boundary condition type.

            Args:
                bc_type (str): Type of boundary condition
                parameter (str): Which field it applies to
                position (int): indices of which cells it applies to
                value (float): Value of boundary condition
            """

            valid_bc_types = ['fixed_value','zero_gradient']
            if bc_type not in valid_bc_types:
                raise Exception("bc_type \'"+bc_type+"\' specified. Valid options for bc_type are:", valid_bc_types)
            valid_parameters = ['T','mdot']
            if parameter not in valid_parameters:
                raise Exception("parameter \'"+parameter+"\' specified. Valid options for parameter are:", valid_parameters)
            if not position:
                raise Exception("Keyword 'position' not specified.")
            if value is None and bc_type=='fixed_value':
                raise Exception("Keyword 'value' is needed for fixed_value type bc.")
            self.bcs.append({'type': bc_type, 'parameter': parameter, 'position': position, 'value': np.array(value)})

        def add_sourceterm_thermal_resistance(self, R:list[float], T_inf:list[float]):
            """Specify a thermal resistance source term.

            Args:
                R (float): List of thermal resistances
                T_inf (float): List of fluid temperatures
            """
            if not len([R]) in [1,self.n]:
                raise Exception("Length of R must be 1 or equal to n")

            if not len([T_inf]) in [1,self.n]:
                raise Exception("Length of T_inf must be 1 or equal to n")

            self.sources.append({'R': R, 'T_inf': T_inf})

        def select_output(self, times:list[float]=None, output_parameters:list[str]=['T']):
            """Specify output times.

            Args:
                times (float): List of times to output data
            """

            self.output_parameters = output_parameters
            class Data(object):
                pass
            self.data = Data()
            self.data.time = np.intersect1d(np.array(times), np.arange(self.outer.t_start, self.outer.t_end+self.outer.dt, self.outer.dt))
            for parameter in output_parameters:
                setattr(self.data,parameter, np.full((len(self.data.time), self.n_other, self.n),np.nan))
                self._flag_save_data = True
                self._q = 0

        def _save_data(self, t:float=None):
            """Save data at specified times.

            Args:
                t (float): Current time
            """

            if self._flag_save_data:
                if t in self.data.time:
                    for parameter in self.output_parameters:
                        getattr(self.data,parameter)[self._q] = getattr(self,parameter)
                    self._q = self._q+1

        def _update_massflow_rate(self, t:float):
            """Update mass flow rate at specified times.

            Args:
                t (float): Current time
            """

            if self.mdot_array.ndim == 0:
                self.mdot = np.tile(self.mdot_array,(np.append(self.n_other,self.domain.shape)))
            elif self.mdot_array.ndim == 2:
                self.mdot = np.interp(t, self.mdot_array[:,0], self.mdot_array[:,1])

        def _update_properties(self):
            """Update properties at each time step."""

            self.T = self.fcns.T(self.h)
            self.rho = self.fcns.rho(self.h)
            self.cp = self.fcns.cp(self.h)

            if hasattr(self, 'diff'):
                self.k = self.fcns.k(self.h)
                self.D[0,:,:] = self.k*self.domain.A[0]/self.domain.dx
                self.D[1,:,:] = self.k*self.domain.A[1]/self.domain.dx

            if hasattr(self, 'conv'):
                self.F[0,:,:] = self.mdot*self.cp
                self.F[1,:,:] = self.mdot*self.cp

        def _update_boundary_nodes(self, t:float=None, dt:float=None):
            """Update boundary nodes.

            Args:
                t (float): Current time
                dt (float): Time step size
            """

            for bc in self.bcs:
                if bc['type'] == 'fixed_value':
                    self.h[bc['position']] = self.fcns.h(bc['value'])
                if bc['type'] == 'fixed_value_timevarying':
                    self.h[bc['position']] = self.fcns.h(np.interp(t,bc['value'][:,0],bc['value'][:,1]))
                if bc['type'] == 'zero_gradient':
                    if bc['position'] == np.s_[:,0]:
                        self.h[bc['position']] = self.h[bc['position']] + (2*self.T[:,1]*self.D[1,:,0] - 2*self.T[:,0]*self.D[1,:,0] - self.F[0,:,1]*self.T[:,1] + self.F[1,:,0]*self.T[:,0]) / (self.rho[:,0]*self.domain.V[0])*dt
                    if bc['position'] == np.s_[:,-1]:
                        self.h[bc['position']] = self.h[bc['position']] + (2*self.T[:,-2]*self.D[0,:,-1] - 2*self.T[:,-1]*self.D[0,:,-1] + self.F[1,:,-2]*self.T[:,-2] - self.F[0,:,-1]*self.T[:,-1]) / (self.rho[:,-1]*self.domain.V[-1])*dt

        def _update_source(self, dt:float=None):
            """Update source term.

            Args:
                dt (float): Time step size
            """

            for source in self.sources:
                self.h = self.h + (source['T_inf']-self.T)*2 / source['R'] * dt/(self.rho*self.domain.V)

        def _solve_equations(self, t:float=None, dt:float=None):
            """Solve equations at each time step.

            Args:
                t (float): Current time
                dt (float): Time step size
            """

            self._update_boundary_nodes(t, dt)
            if hasattr(self, 'diff'):
                self.h = self.h + self.diff(self.T, self.D)/(self.rho*self.domain.V)*dt
            if hasattr(self, 'conv'):
                self._update_massflow_rate(t)
                self.h = self.h + self.conv(self.T, self.F)/(self.rho*self.domain.V)*dt
            if self.sources is not None:
                self._update_source(dt)
Phase
Source code in openterrace/openterrace.py 
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class Phase:
    instances = []
    """Main class to define either the fluid or bed phase."""

    def __init__(self, outer=None, n:int=None, n_other:int=None, type:str=None):
        """Initialise a phase with number of control points and type.

        Args:
            outer (object): Outer class
            n (int): Number of discretisations for the given phase
            n_other (int): Number of discretisations for the other phase
            type (str): Type of phase
        """

        self.outer = outer
        self.__class__.instances.append(self)
        self.n = n
        self.n_other = n_other

        self.phi = 1
        self.bcs = []
        self.sources = []

        self._flag_save_data = False
        self.type = type

    def select_substance_on_the_fly(self, cp:float=None, rho:float=None, k:float=None):
        """Defines and selects a new substance on-the-fly. This is useful for defining a substance for testing purposes with temperature independent properties.

        Args:
            cp (float): Specific heat capacity in J/(kg K)
            rho (float): Density in kg/m^3
            k (float): Thermal conductivity in W/(m K)
        """
        class dummy:
            pass
        self.fcns = dummy()
        self.fcns.h = lambda T: np.ones_like(T)*T*cp
        self.fcns.T = lambda h: np.ones_like(h)*h/cp
        self.fcns.cp = lambda h: np.ones_like(h)*cp
        self.fcns.k = lambda h: np.ones_like(h)*k
        self.fcns.rho = lambda h: np.ones_like(h)*rho

    def select_substance(self, substance:str=None):
        """Selects one of the predefined substancers.

        Args:
            substance (str): Substance name
        """

        valid_substances = globals()[self.type+'_substances'].__all__
        if not substance:
            raise Exception("Keyword 'substance' not specified.")
        if not substance in valid_substances:
            raise Exception(substance+" specified as "+self.type+" substance. Valid "+self.type+" substances are:", valid_substances)
        self.fcns = getattr(globals()[self.type+'_substances'], substance)

    def select_h_coeff(self, h_exp:str=None, value:float=None):
        """Selects an expression for the heat transfer coefficient.

        Args:
            h_exp (str): Heat transfer coefficient expression
            value (float): Heat transfer coefficient value
        """

        valid_correlations = ['constant']
        if correlation not in valid_correlations:
            raise Exception("correlation \'"+correlation+"\' specified. Valid options for correlation are:", valid_correlations)
        self.fcns.h_correlation = getattr(globals()['heat_transfer_correlations'], correlation)

    def select_domain_shape(self, domain:str=None, **kwargs):
        """Select domain shape and initialise constants.

        Args:
            domain (str): Domain type
            **kwargs (float): Dimensions of domain to be specified depnding on the domain type
        """

        if not domain:
            raise Exception("Keyword 'domain' not specified.")
        if not domain in globals()['domains'].__all__:
            raise Exception("domain \'"+domain+"\' specified. Valid options for domain are:", self.valid_domains)

        kwargs['n'] = self.n 
        self.domain = getattr(globals()['domains'], domain)
        self.domain.type = domain
        self.domain.validate_input(kwargs, domain)
        self.domain.shape = self.domain.shape(kwargs)
        self.domain.dx = self.domain.dx(kwargs)
        self.domain.A = self.domain.A(kwargs)
        self.domain.V = self.domain.V(kwargs)
        self.domain.V0 = self.domain.V0(kwargs)
        self.node_pos = self.domain.node_pos(kwargs)

    def select_porosity(self, phi:float=1):
        """Select porosity from 0 to 1, e.g. filling the domain with the phase up to a certain degree.

        Args:
            phi (float): Porosity value
        """

        self.domain.V = self.domain.V*phi
        self.phi = phi

    def select_schemes(self, diff:str=None, conv:str=None):
        """Imports the specified diffusion and convection schemes.

        Args:
            diff (str): Differenctial scheme
            conv (str): Convection scheme
        """

        if self.domain.type == 'lumped':
            raise Exception("'lumped' has been selected as domain type. Please don't specify a discretisation scheme.")

        if diff is not None:
            try:
                self.diff = getattr(getattr(globals()['diffusion_schemes'], diff), diff)
            except:
                raise Exception("Diffusion scheme \'"+diff+"\' specified. Valid options for diffusion schemes are:", diffusion_schemes.__all__)

        if conv is not None:
            try:
                self.conv = getattr(getattr(globals()['convection_schemes'], conv), conv)
            except:
                raise Exception("Convection scheme \'"+conv+"\' specified. Valid options for convection schemes are:", convection_schemes.__all__)

    def select_initial_conditions(self, T:list[float]=None):
        """Initialises temperature field.

        Args:
            T (float): List of length n with initial temperatures
        """

        if np.array(T).size == 1:
            self.T = np.tile(T,(np.append(self.n_other,self.domain.shape)))   
        elif np.array(T).size == self.n:
            self.T = np.tile(T,(np.append(self.n_other,1)))
        else: Exception("Length of T must be 1 or equal to n")

        self.h = self.fcns.h(self.T)
        self.T = self.fcns.T(self.h)
        self.rho = self.fcns.rho(self.h)
        self.cp = self.fcns.cp(self.h)
        self.k = self.fcns.k(self.h)
        self.D = np.zeros(((2,)+(self.T.shape)))
        self.F = np.zeros(((2,)+(self.T.shape)))
        self.S = np.zeros(self.T.shape)

    def select_massflow(self, mdot:list[float]=None):
        """Initialises mass flow rate field.

        Args:
            mdot (float): Array of mass flow rate. Column 0 is time and column 1 is mass flow rate
        """

        self.mdot_array = np.array(mdot)

    def select_bc(self, bc_type:str=None, parameter:str=None, position=None, value:float=None):
        """Specify boundary condition type.

        Args:
            bc_type (str): Type of boundary condition
            parameter (str): Which field it applies to
            position (int): indices of which cells it applies to
            value (float): Value of boundary condition
        """

        valid_bc_types = ['fixed_value','zero_gradient']
        if bc_type not in valid_bc_types:
            raise Exception("bc_type \'"+bc_type+"\' specified. Valid options for bc_type are:", valid_bc_types)
        valid_parameters = ['T','mdot']
        if parameter not in valid_parameters:
            raise Exception("parameter \'"+parameter+"\' specified. Valid options for parameter are:", valid_parameters)
        if not position:
            raise Exception("Keyword 'position' not specified.")
        if value is None and bc_type=='fixed_value':
            raise Exception("Keyword 'value' is needed for fixed_value type bc.")
        self.bcs.append({'type': bc_type, 'parameter': parameter, 'position': position, 'value': np.array(value)})

    def add_sourceterm_thermal_resistance(self, R:list[float], T_inf:list[float]):
        """Specify a thermal resistance source term.

        Args:
            R (float): List of thermal resistances
            T_inf (float): List of fluid temperatures
        """
        if not len([R]) in [1,self.n]:
            raise Exception("Length of R must be 1 or equal to n")

        if not len([T_inf]) in [1,self.n]:
            raise Exception("Length of T_inf must be 1 or equal to n")

        self.sources.append({'R': R, 'T_inf': T_inf})

    def select_output(self, times:list[float]=None, output_parameters:list[str]=['T']):
        """Specify output times.

        Args:
            times (float): List of times to output data
        """

        self.output_parameters = output_parameters
        class Data(object):
            pass
        self.data = Data()
        self.data.time = np.intersect1d(np.array(times), np.arange(self.outer.t_start, self.outer.t_end+self.outer.dt, self.outer.dt))
        for parameter in output_parameters:
            setattr(self.data,parameter, np.full((len(self.data.time), self.n_other, self.n),np.nan))
            self._flag_save_data = True
            self._q = 0

    def _save_data(self, t:float=None):
        """Save data at specified times.

        Args:
            t (float): Current time
        """

        if self._flag_save_data:
            if t in self.data.time:
                for parameter in self.output_parameters:
                    getattr(self.data,parameter)[self._q] = getattr(self,parameter)
                self._q = self._q+1

    def _update_massflow_rate(self, t:float):
        """Update mass flow rate at specified times.

        Args:
            t (float): Current time
        """

        if self.mdot_array.ndim == 0:
            self.mdot = np.tile(self.mdot_array,(np.append(self.n_other,self.domain.shape)))
        elif self.mdot_array.ndim == 2:
            self.mdot = np.interp(t, self.mdot_array[:,0], self.mdot_array[:,1])

    def _update_properties(self):
        """Update properties at each time step."""

        self.T = self.fcns.T(self.h)
        self.rho = self.fcns.rho(self.h)
        self.cp = self.fcns.cp(self.h)

        if hasattr(self, 'diff'):
            self.k = self.fcns.k(self.h)
            self.D[0,:,:] = self.k*self.domain.A[0]/self.domain.dx
            self.D[1,:,:] = self.k*self.domain.A[1]/self.domain.dx

        if hasattr(self, 'conv'):
            self.F[0,:,:] = self.mdot*self.cp
            self.F[1,:,:] = self.mdot*self.cp

    def _update_boundary_nodes(self, t:float=None, dt:float=None):
        """Update boundary nodes.

        Args:
            t (float): Current time
            dt (float): Time step size
        """

        for bc in self.bcs:
            if bc['type'] == 'fixed_value':
                self.h[bc['position']] = self.fcns.h(bc['value'])
            if bc['type'] == 'fixed_value_timevarying':
                self.h[bc['position']] = self.fcns.h(np.interp(t,bc['value'][:,0],bc['value'][:,1]))
            if bc['type'] == 'zero_gradient':
                if bc['position'] == np.s_[:,0]:
                    self.h[bc['position']] = self.h[bc['position']] + (2*self.T[:,1]*self.D[1,:,0] - 2*self.T[:,0]*self.D[1,:,0] - self.F[0,:,1]*self.T[:,1] + self.F[1,:,0]*self.T[:,0]) / (self.rho[:,0]*self.domain.V[0])*dt
                if bc['position'] == np.s_[:,-1]:
                    self.h[bc['position']] = self.h[bc['position']] + (2*self.T[:,-2]*self.D[0,:,-1] - 2*self.T[:,-1]*self.D[0,:,-1] + self.F[1,:,-2]*self.T[:,-2] - self.F[0,:,-1]*self.T[:,-1]) / (self.rho[:,-1]*self.domain.V[-1])*dt

    def _update_source(self, dt:float=None):
        """Update source term.

        Args:
            dt (float): Time step size
        """

        for source in self.sources:
            self.h = self.h + (source['T_inf']-self.T)*2 / source['R'] * dt/(self.rho*self.domain.V)

    def _solve_equations(self, t:float=None, dt:float=None):
        """Solve equations at each time step.

        Args:
            t (float): Current time
            dt (float): Time step size
        """

        self._update_boundary_nodes(t, dt)
        if hasattr(self, 'diff'):
            self.h = self.h + self.diff(self.T, self.D)/(self.rho*self.domain.V)*dt
        if hasattr(self, 'conv'):
            self._update_massflow_rate(t)
            self.h = self.h + self.conv(self.T, self.F)/(self.rho*self.domain.V)*dt
        if self.sources is not None:
            self._update_source(dt)
instances = [] class-attribute instance-attribute

Main class to define either the fluid or bed phase.

__init__(outer=None, n=None, n_other=None, type=None)

Initialise a phase with number of control points and type.

Parameters:

Name Type Description Default
outer object

Outer class

 None
n int

Number of discretisations for the given phase

 None
n_other int

Number of discretisations for the other phase

 None
type str

Type of phase

 None
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def __init__(self, outer=None, n:int=None, n_other:int=None, type:str=None):
    """Initialise a phase with number of control points and type.

    Args:
        outer (object): Outer class
        n (int): Number of discretisations for the given phase
        n_other (int): Number of discretisations for the other phase
        type (str): Type of phase
    """

    self.outer = outer
    self.__class__.instances.append(self)
    self.n = n
    self.n_other = n_other

    self.phi = 1
    self.bcs = []
    self.sources = []

    self._flag_save_data = False
    self.type = type
add_sourceterm_thermal_resistance(R, T_inf)

Specify a thermal resistance source term.

Parameters:

Name Type Description Default
R float

List of thermal resistances

 required
T_inf float

List of fluid temperatures

 required
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def add_sourceterm_thermal_resistance(self, R:list[float], T_inf:list[float]):
    """Specify a thermal resistance source term.

    Args:
        R (float): List of thermal resistances
        T_inf (float): List of fluid temperatures
    """
    if not len([R]) in [1,self.n]:
        raise Exception("Length of R must be 1 or equal to n")

    if not len([T_inf]) in [1,self.n]:
        raise Exception("Length of T_inf must be 1 or equal to n")

    self.sources.append({'R': R, 'T_inf': T_inf})
select_bc(bc_type=None, parameter=None, position=None, value=None)

Specify boundary condition type.

Parameters:

Name Type Description Default
bc_type str

Type of boundary condition

 None
parameter str

Which field it applies to

 None
position int

indices of which cells it applies to

 None
value float

Value of boundary condition

 None
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def select_bc(self, bc_type:str=None, parameter:str=None, position=None, value:float=None):
    """Specify boundary condition type.

    Args:
        bc_type (str): Type of boundary condition
        parameter (str): Which field it applies to
        position (int): indices of which cells it applies to
        value (float): Value of boundary condition
    """

    valid_bc_types = ['fixed_value','zero_gradient']
    if bc_type not in valid_bc_types:
        raise Exception("bc_type \'"+bc_type+"\' specified. Valid options for bc_type are:", valid_bc_types)
    valid_parameters = ['T','mdot']
    if parameter not in valid_parameters:
        raise Exception("parameter \'"+parameter+"\' specified. Valid options for parameter are:", valid_parameters)
    if not position:
        raise Exception("Keyword 'position' not specified.")
    if value is None and bc_type=='fixed_value':
        raise Exception("Keyword 'value' is needed for fixed_value type bc.")
    self.bcs.append({'type': bc_type, 'parameter': parameter, 'position': position, 'value': np.array(value)})
select_domain_shape(domain=None, **kwargs)

Select domain shape and initialise constants.

Parameters:

Name Type Description Default
domain str

Domain type

 None
**kwargs float

Dimensions of domain to be specified depnding on the domain type

 {}
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def select_domain_shape(self, domain:str=None, **kwargs):
    """Select domain shape and initialise constants.

    Args:
        domain (str): Domain type
        **kwargs (float): Dimensions of domain to be specified depnding on the domain type
    """

    if not domain:
        raise Exception("Keyword 'domain' not specified.")
    if not domain in globals()['domains'].__all__:
        raise Exception("domain \'"+domain+"\' specified. Valid options for domain are:", self.valid_domains)

    kwargs['n'] = self.n 
    self.domain = getattr(globals()['domains'], domain)
    self.domain.type = domain
    self.domain.validate_input(kwargs, domain)
    self.domain.shape = self.domain.shape(kwargs)
    self.domain.dx = self.domain.dx(kwargs)
    self.domain.A = self.domain.A(kwargs)
    self.domain.V = self.domain.V(kwargs)
    self.domain.V0 = self.domain.V0(kwargs)
    self.node_pos = self.domain.node_pos(kwargs)
select_h_coeff(h_exp=None, value=None)

Selects an expression for the heat transfer coefficient.

Parameters:

Name Type Description Default
h_exp str

Heat transfer coefficient expression

 None
value float

Heat transfer coefficient value

 None
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def select_h_coeff(self, h_exp:str=None, value:float=None):
    """Selects an expression for the heat transfer coefficient.

    Args:
        h_exp (str): Heat transfer coefficient expression
        value (float): Heat transfer coefficient value
    """

    valid_correlations = ['constant']
    if correlation not in valid_correlations:
        raise Exception("correlation \'"+correlation+"\' specified. Valid options for correlation are:", valid_correlations)
    self.fcns.h_correlation = getattr(globals()['heat_transfer_correlations'], correlation)
select_initial_conditions(T=None)

Initialises temperature field.

Parameters:

Name Type Description Default
T float

List of length n with initial temperatures

 None
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def select_initial_conditions(self, T:list[float]=None):
    """Initialises temperature field.

    Args:
        T (float): List of length n with initial temperatures
    """

    if np.array(T).size == 1:
        self.T = np.tile(T,(np.append(self.n_other,self.domain.shape)))   
    elif np.array(T).size == self.n:
        self.T = np.tile(T,(np.append(self.n_other,1)))
    else: Exception("Length of T must be 1 or equal to n")

    self.h = self.fcns.h(self.T)
    self.T = self.fcns.T(self.h)
    self.rho = self.fcns.rho(self.h)
    self.cp = self.fcns.cp(self.h)
    self.k = self.fcns.k(self.h)
    self.D = np.zeros(((2,)+(self.T.shape)))
    self.F = np.zeros(((2,)+(self.T.shape)))
    self.S = np.zeros(self.T.shape)
select_massflow(mdot=None)

Initialises mass flow rate field.

Parameters:

Name Type Description Default
mdot float

Array of mass flow rate. Column 0 is time and column 1 is mass flow rate

 None
Source code in openterrace/openterrace.py 
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def select_massflow(self, mdot:list[float]=None):
    """Initialises mass flow rate field.

    Args:
        mdot (float): Array of mass flow rate. Column 0 is time and column 1 is mass flow rate
    """

    self.mdot_array = np.array(mdot)
select_output(times=None, output_parameters=['T'])

Specify output times.

Parameters:

Name Type Description Default
times float

List of times to output data

 None
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def select_output(self, times:list[float]=None, output_parameters:list[str]=['T']):
    """Specify output times.

    Args:
        times (float): List of times to output data
    """

    self.output_parameters = output_parameters
    class Data(object):
        pass
    self.data = Data()
    self.data.time = np.intersect1d(np.array(times), np.arange(self.outer.t_start, self.outer.t_end+self.outer.dt, self.outer.dt))
    for parameter in output_parameters:
        setattr(self.data,parameter, np.full((len(self.data.time), self.n_other, self.n),np.nan))
        self._flag_save_data = True
        self._q = 0
select_porosity(phi=1)

Select porosity from 0 to 1, e.g. filling the domain with the phase up to a certain degree.

Parameters:

Name Type Description Default
phi float

Porosity value

 1
Source code in openterrace/openterrace.py 
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def select_porosity(self, phi:float=1):
    """Select porosity from 0 to 1, e.g. filling the domain with the phase up to a certain degree.

    Args:
        phi (float): Porosity value
    """

    self.domain.V = self.domain.V*phi
    self.phi = phi
select_schemes(diff=None, conv=None)

Imports the specified diffusion and convection schemes.

Parameters:

Name Type Description Default
diff str

Differenctial scheme

 None
conv str

Convection scheme

 None
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def select_schemes(self, diff:str=None, conv:str=None):
    """Imports the specified diffusion and convection schemes.

    Args:
        diff (str): Differenctial scheme
        conv (str): Convection scheme
    """

    if self.domain.type == 'lumped':
        raise Exception("'lumped' has been selected as domain type. Please don't specify a discretisation scheme.")

    if diff is not None:
        try:
            self.diff = getattr(getattr(globals()['diffusion_schemes'], diff), diff)
        except:
            raise Exception("Diffusion scheme \'"+diff+"\' specified. Valid options for diffusion schemes are:", diffusion_schemes.__all__)

    if conv is not None:
        try:
            self.conv = getattr(getattr(globals()['convection_schemes'], conv), conv)
        except:
            raise Exception("Convection scheme \'"+conv+"\' specified. Valid options for convection schemes are:", convection_schemes.__all__)
select_substance(substance=None)

Selects one of the predefined substancers.

Parameters:

Name Type Description Default
substance str

Substance name

 None
Source code in openterrace/openterrace.py 
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def select_substance(self, substance:str=None):
    """Selects one of the predefined substancers.

    Args:
        substance (str): Substance name
    """

    valid_substances = globals()[self.type+'_substances'].__all__
    if not substance:
        raise Exception("Keyword 'substance' not specified.")
    if not substance in valid_substances:
        raise Exception(substance+" specified as "+self.type+" substance. Valid "+self.type+" substances are:", valid_substances)
    self.fcns = getattr(globals()[self.type+'_substances'], substance)
select_substance_on_the_fly(cp=None, rho=None, k=None)

Defines and selects a new substance on-the-fly. This is useful for defining a substance for testing purposes with temperature independent properties.

Parameters:

Name Type Description Default
cp float

Specific heat capacity in J/(kg K)

 None
rho float

Density in kg/m^3

 None
k float

Thermal conductivity in W/(m K)

 None
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def select_substance_on_the_fly(self, cp:float=None, rho:float=None, k:float=None):
    """Defines and selects a new substance on-the-fly. This is useful for defining a substance for testing purposes with temperature independent properties.

    Args:
        cp (float): Specific heat capacity in J/(kg K)
        rho (float): Density in kg/m^3
        k (float): Thermal conductivity in W/(m K)
    """
    class dummy:
        pass
    self.fcns = dummy()
    self.fcns.h = lambda T: np.ones_like(T)*T*cp
    self.fcns.T = lambda h: np.ones_like(h)*h/cp
    self.fcns.cp = lambda h: np.ones_like(h)*cp
    self.fcns.k = lambda h: np.ones_like(h)*k
    self.fcns.rho = lambda h: np.ones_like(h)*rho
__init__(t_start=0, t_end=None, dt=None)

Initialise with various control parameters.

Parameters:

Name Type Description Default
t_start float

Start time in s

 0
t_end float

End time in s

 None
dt float

Time step size in s

 None
Source code in openterrace/openterrace.py 
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def __init__(self, t_start:float=0, t_end:float=None, dt:float=None):
    """Initialise with various control parameters.

    Args:
        t_start (float): Start time in s
        t_end (float): End time in s
        dt (float): Time step size in s
    """
    self.t_start = t_start
    self.t_end = t_end
    self.dt = dt
    self.coupling = []
    self.flag_coupling = False
create_phase(n=None, n_other=1, type=None)

Creates a fluid or bed phase.

Parameters:

Name Type Description Default
n int

Number of discretisations

 None
n_other int

Number of discretisations of interacting phase. If you are defining a bed phase within a tank. Then n_other is the number of discretisations of the fluid phase.

 1
type str

Phase type

 None
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def create_phase(self, n:int=None, n_other:int=1, type:str=None):
    """Creates a fluid or bed phase.

    Args:
        n (int): Number of discretisations
        n_other (int): Number of discretisations of interacting phase. If you are defining a bed phase within a tank. Then n_other is the number of discretisations of the fluid phase.
        type (str): Phase type
    """

    valid_types = ['fluid','bed']
    if type not in valid_types:
        raise Exception("Type \'"+type+"\' specified. Valid options for types are:", valid_types)
    return self.Phase(self, n, n_other, type)
run_simulation()

If you want to run the simulation, you need to call this function. If data output is specified using the select_output function, the data will live in that specific phase instance. For more details on how to access the data, please refer to the tutorials.

Source code in openterrace/openterrace.py 
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def run_simulation(self):
    """If you want to run the simulation, you need to call this function. If data output is specified using the select_output function, the data will live in that specific phase instance. For more details on how to access the data, please refer to the tutorials."""


    for t in tqdm.tqdm(np.arange(self.t_start, self.t_end+self.dt, self.dt)):

        for phase_instance in self.Phase.instances:
            phase_instance._save_data(t)
            phase_instance._solve_equations(t, self.dt)
            phase_instance._update_properties()
        if self.flag_coupling:
            self._coupling()
select_coupling(fluid_phase=None, bed_phase=None, h_exp=None, h_value=None)

Selects coupling of a fluid and bed phase

Parameters:

Name Type Description Default
fluid_phase int

phase number

 None
bed_phase int

phase number

 None
h_exp str

Predefined function for convective heat transfer

 None
h_value float

Convective heat transfer coefficient in W/(m^2 K)

 None
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def select_coupling(self, fluid_phase:int=None, bed_phase:int=None, h_exp:str=None, h_value:float=None):
    """Selects coupling of a fluid and bed phase

    Args:
        fluid_phase (int): phase number
        bed_phase (int): phase number
        h_exp (str): Predefined function for convective heat transfer
        h_value (float): Convective heat transfer coefficient in W/(m^2 K)
    """

    valid_h_exp = ['constant']
    if h_exp not in valid_h_exp:
        raise Exception("h_exp \'"+h_exp+"\' specified. Valid options for h_exp are:", valid_h_exp)

    self.coupling.append({"fluid_phase":fluid_phase, "bed_phase":bed_phase, "h_exp":h_exp, "h_value":h_value})
    self.flag_coupling = True