[ben_tu]

Hi,

I'm doing a CHT Simulation with two different meshes for Solid and Fluid. On top of that I implemented a two-phase flow, because the coolant gas of my NGV is CO2. For better accuracy the specific heat capacity for the mixture is modeled via an expression, an example:

((2.35677352E+00)+(8.98459677E-03)[K^-1]*(Temperature)-(7.12356269E-06)[K^-2]*(Temperature)^2+(2.45919022E-09)[K^-3]*(Temperature)^3-(1.43699548E-13)[K^-4]*(Temperature)^4)*188.9[J kg^-1 K^-1]

The problem is that cfx tries to solve these expressions for both meshes. So it produces an error while it is trying to solve the expression on the solid mesh. My question is, how can I change the expression so that it only takes the temperature from the fluid parts?


I've already tried different things like

temperature@fluid
temperature@REGION:Main
Fluid.temperature

but nothing worked.

Maybe some of you guys have a solution, thank you for your time and answers!

[ghorrocks]

Can you post an image of what you are modelling and the CCL of your model (a constant specific heat model would be good).

[ben_tu]

I modeled the specific heats with these 5 equations. 4 for Air and 1 for the CO2. As you can see in the pictures the simulation of the nozzle guide vane consist of two meshes. One for the vane called solid, and one for the fluid.

I added the solid mesh recently, before it was added everything was fine. But now cfx compute the specific heat equations also for the solid part, which produces an error.

So thats my case, and I want to change the expressions for the Specific heats, so that cfx compute them only for the fluid part.

[ghorrocks]

If you have correctly defined the solid region as a solid it will not calculate the Air values in that region. So this is an XY problem (http://xyproblem.info/) - the issue has nothing to do with turning the equation off in the solid region, there is a problem with your setup which is causing this error.

Please attach your CCL as I requested in the previous post. We can check what you are doing with the CCL - that is why I asked for it.