I am simulating a 2D first stage turbine as seen in Fig. 1. It is consisted of 4 domains; at the left, there is a fluid domain and a solid domain (stator vane) and at the right, there is also a fluid domain and a solid domain (rotor blade). The two domains at the right are moving down by using a sliding mesh technique. After initialization, once I start the iteration, I get a warning saying:
WARNING: The solid velocity has a significant normal component on 10708 faces of face zone 21.
The maximum angle between the velocity and face surface is 90.0 deg at ( 2.364e-02, 3.669e-02, 0.000e+00).
The solver may not achieve global energy conservation as a result.
The tolerance for this check (currently 20.0 deg) is controlled by the rpvar 'wall/vnormal-tolerance'.
Please check your setup. This warning will not be written again.
and then after couple of iteration, I get divergence because the temperature of moving solid gets unrealistically low (1 Kelvin).
The boundary conditions are simple:
1- inlet (the left vertical edge at the left of the stationary domains): pressure inlet: 16 atm (Also, I tried mass flow inlet=15 kg/s and velocity inlet = 10 m/s as well).
2- outlet (the right vertical edge at the right of the moving domains): pressure outlet: 3.5 atm.
3- The upper and lower edges of the fluid domains are periodic boundary condition.
4- the interface (its length is 0.05 m) between the moving and stationary domains is "periodic repeat".
5- the two solids domain: constant heat flux (I also tried different values for it)
6- the moving domains moves down at a speed of 553 m/s.
7- time step size = 3.5 e-6 seconds.
8- I tried different schemes (coupled, simple, simplec, etc) but I got the same warning and divergence!!
I also tried a denser mesh for the moving solid body but didn't solve the issue.