Generating a uFVM Solver

This page provides a tutorial in the basics of simulating an unstructured-mesh configuration using uFVM solvers. The process of initializing and running a simulation in both PerfectGas and CO₂ solvers is identical.

Unstructured-Mesh

First you should create an unstructured-mesh for a desired geometry that you are willing to study. We primarily used an open source application named Gmsh which generates a mesh file with .msh extention and created a parser which takes the standard output file from Gmsh and converts it into an unstructured-mesh file with .dat extention.

The solver only accepts a mesh file with name grid.dat and should be located in the same directory along with the source code. There are various ways in which we generate an mesh, these are mentioned in Mesh Generation.

Note

A sample unstructured-mesh is given in the source code to make things easier at the start.

Freestream Conditions

After generating the mesh you must now define the problem by inserting the initial freestream values like Pressure, Temperature, Mach number, etc,. In CO₂ solver you can even adjust the Mass fractions for all eight species. The initial values must be added in the file input_values.h located in the base_solver directory. Here is an example of some initial variables being defined in PerfectGas solver:

/*---------- PerfectGas solver-----------*/
temp_ini = 131.70;
Pr_ini = 199.4345;
mach_no = 6.0;
wall_temp = 300.00;
R_ini = 287.00;
rho_ini = Pr_ini/(R_ini*temp_ini);
gamma_ini = 1.40;
viscosity_ref = 0.00001716;
prandtl_no = 0.71;

Caution

Do not change or remove any other constant values defined in input_values.h it may cause compilation errors and the solver will not work.

Warning

Should change the variable for number of iterations to input_values.h.

Code Generation and Compilation

To generate the solver code and run it on single/multi-core CPU’s you must execute the python code and the translate the generated OP2 compliant code using the OP2 code translator and run it on the target architecture.

# Generating OP2 compliant code
python3 generate_solver.py

# Translating the generated code
cd code/
make clean
python2.7 ~/softwares/OP2-Common/translator/c/python/op2.py cfdsolver.cpp

# Executing the Solver in sequential
make cfdsolver_seq
./cfdsolver_seq

Post Processing

After the simulation is completed the solver generates the results in the code/results.dat file. The results can be post-processed using the TecPlot 360 software or an open source software ParaView.