[vipulparmar174]

Hello!
I'm trying to study the flow path of Charge in the engine and in that for moving piston I have to give dynamic meshing to the piston but the solver will not solve it completely when the crank angle reaches to 191.5 degree it will stop solving and the dialog box with a message will open and it says negative dynamic cell zone created and after that the solver will not solve it further.
Please, anybody, help me out how to solve this problem.

[ghorrocks]

FAQ: https://www.cfd-online.com/Wiki/Ansy..._went_wrong.3F

But I have done a lot of IC engine modelling so in your case I suspect you find that CFX can stretch a mesh well but it is poor at compressing it and often results in folding meshes. The easiest way I found to avoid this is by starting the simulation at TDC and that way you only ever stretch the mesh and never compress it.

That TDC trick works on any version of CFX. I understand recent versions of CFX have some new mesh motion options which may also help but I have not looked into them.

[anjinoop]

Dear All,

I am using CFX for supercritical co2 fluid. I am using polynomials for properties and data is taken from NIST database

I am getting the above mentioned error. But error disappears when i use any other default fluid.

Please help in this regard

Jinoop

[ghorrocks]

The negative volume element error has nothing to do with the fluid. It is just that the mesh has turned inside out. If changing the fluid affects this, then you must have some coupling to the fluid, maybe FSI, rigid bodies or something similar.