Moving mesh and thermodynamic issues...
 

Hi,

I am working on simulations with moving meshes. I have noticed several strange things using moving mesh:

I did simple simulation of a piston which first compress the gas and then moving backward letting gas to expand. There is no heat flux, just motion of a mesh. When I monitor the pressure and total volume I do get positive work!!? How is it possible...?

The other thing is heat flux through moving boundary. I have made the "total heat flux report" on each of boundaries and I have noticed relatively large heat flux through my moving boundary (even so it is set to adiabatic) why is that?

I did it via Report/Fluxes/TotalHeatTransferRate - does any body know how to monitor this particular flux and write it to file? ( i tried surface integrals... averaging and non of those gives me this strange flux)

I will be appreciated for help with those problems...

Hi loook,
have you tried disabling Energy from Equation menu?

Regards

no I did not, because I need to solve the energy. This is a problem I came up with during other simulation. In this other simulation i have two heat exchangers cold one and hot one. I got there work from PdV diagram and work from heat fluxes from heat exchangers (Qh-Qc). I found that they are different by 20% !. So it is kind of strange that I get different amount of work depending on how do I calculate it.

This is why I have tuned off the heat exchangers (in order to get adiabatic case) and got this strange results....