I am doing a porous media heat transfer simulation using K-omega SST and SIMPLE algorithm with a Second order scheme for all parameters and bounded second order for transient. All CPUs are loaded equally about 2.2%. The mesh count is 375000 elements among which 60000 are solid domain and not porous media. Since I am using the LTNE model I have 690000 elements finally that only use about 12% of my 128GB RAM.