[Jiricbeng]

Hello,

I am simulating transient conjugate heat transfer of a vehicle flying from subsonic to hypersonic regime (from Mach number 0.3 to 5).
The model consists of pressure-far-field boundary condition and walls of the vehicle. The solid of the vehicle is connected by coupled interface (node to node connection, fluid and solid were meshed as one part). The boundary condition are set by transient profile on pressure-far-field, so Pressure, Temperature and Mach number are changing in time.

The vehicle has rotational symmetry and the flow is also symmetric - zero angle of attack. Therefore I created 2D axisymmetric model but I created also 3D 180deg segment model (because another subsequent analysis will include non-zero angle of attack). I want to correlate 2D axisym. model with 3D model. The mesh of 3D model is made by sweep and the sizing is the same as in 2D axisym. model. In both cases it is full hexa mesh.

Converging 2D axisym. model is not any issue, but I cannot reasonably converge 3D model. I did sensitivity study for time-step sizes and for example time-step 0.1s still works fine for 2D axisym. but it does not work for 3D, the results of heat flux are significantly different. It is obvious from contour plots that the flow field is not converged.

Any ideas/comments/recommendation to this issue are appreciated !