With OpenTerrace installed, you can start setting up your simulation. The following shows a complete example of an OpenTerrace simulation setup.
Define global parameters
t_end(required): End time of the simulation in seconds
dt(required): Time step size in seconds
n_fluid(optional): Number of discretisations for the fluid phase (omit if only solving the bed phase)
n_bed(optional): Number of discretisations for the bed phase (omit if only solving the fluid phase)
n_bed should be specified. If either is omitted that phase wont be simulated.
Setup the fluid phase
1. Select a fluid
substance(required): Name of substance for the phase we are defining
We select a substance for our simulation. We can either use of the predefined substances such as
'air' or define one on the fly with temperature-independent properties, e.g.:
rho(required): Density in kg/m^3
cp(required): Specific heat capacity in J/(kg*K)
k(required): Thermal conductivity in W/(m*K)
2. Select a domain shape
domain(required): Domain used for the phase
We choose a domain shape using on of the primivite shapes that come built into OpenTerrace. See this list for avialable shapes. Note, each domain will have additional parameters required, e.g. a sphere requires a radius to be defined. You will be prompted to add these if you are missing some.
3. Select a porosity (
phi(required): Porosity m^3/m^3 (e.g. set to 0.4 and the fluid only occupies 40% of the volume)
The domain may be only partially filled with fluid as a bed phase occupies some space. This command may be omitted in which case the fluid occupies the whole domain.
4. Select discretisation schemes
diff(required): Discretisation scheme for the diffusion term
conv(required): Discretisation scheme for the convective term
5. Select intial conditions
T(required): Temperature in K
mdot(optional): mass flow rate in kg/s
We choose initial conditions for our simulation in terms of temperature and mass flow rate.
6. Select boundary conditions
bc_type(required): Name of the boundary condition type
parameter(required): Parameter for which you are specifying boundary condition
position(required): Can be either
(slice(None, None, None), 0)for lower bc (e.g. 1d cylinder) or centre boundary (e.g. 1d sphere), or
(slice(None, None, None), -1)for upper bc (e.g. 1d cylinder) or surface boundary (e.g. 1d sphere).
value(required): Specifies the value for
Setup the bed phase
The bed phase is setup in a similar fashion to the fluid phase. An example is given below:
Note we use neumann type bcs for both boundaries. The coupling between the phases is a source term, which will be added using the
coupling keyword next.
Define phase interactions and post-processing
h_coeff(required): Correlation for the heat transfer coefficient (note currently only
h_value(required): Heat transfer coefficient in W/(m^2*K)
save_int(required): Save interval (number of time steps between two successive write outs)
file_name(optional): Specfies a filename for the animation
Finally, we define how to visualise the results. Here, we save results every 6000 timestep (dt=0.025 s) e.g. every 150 s.