[usamaubk]

Hello,
I am modelling a simple engine which only consists of cylinder liner, cylinder head and a piston. I have all the experimental data to model it. The experimental CR ratio is 14.3, but when I set CR 14.3 in ConvergeCFD the pressure is overestimated. CR in converge is properly configured. Setting the CR to around 12.1 matches the experimental pressure results. This maybe due to the fact that I am not considering the blowby effects in the simulation. So, my question is there any way I can incorporate the blowby effect into the converge CFD simulation so that by doing that even if I set high CR i will get the same pressure curves as of experimentaion. I have heard that there is a tuneable blowby model in converge CFD. SO can somebody guide me in this specific case.

[ksrivast]

Hello Usama,

Blowby effect can be incorporated in your CONVERGE simulation using our crevice model. With the crevice model, you can simulate flow between piston, piston rings, and cylinder without having to resolve the crevice regions on the CFD domain directly.

You can enable the crevice model under Case setup > Application type > Crank angle-based (IC engine) > Use crevice model, or by setting crevice_flag=1 in engine.in. Your simulation will then require a crevice.in file, that contains geometric and thermodynamic inputs for the crevice model.

For more details on the crevice model, please have a look at our manual. If you require assistance with setting up the crevice model for your simulations, please reach out to us at support@convergecfd.com. Please use your official email for all correspondence with Convergent Science. Please state your request, attach a case setup if possible and mention the cfd-online thread, as reference.

Sincerely,