# Sliding mesh with conjugate heat transfer

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October 21, 2019, 23:07
Sliding mesh with conjugate heat transfer
#1
New Member

Ramy
Join Date: Nov 2016
Posts: 5
Rep Power: 9
Dear all,

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'.

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 and tried a conformal and nonconformal meshes for the moving body but none of them worked!!

Thank you.
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October 26, 2019, 18:31
#2
New Member

Ramy
Join Date: Nov 2016
Posts: 5
Rep Power: 9
For anybody having the same problem in the future, the solution is that you need to adjust the geometry and the mesh to make the coordinates (you need to make sure that in the solver the coordinates are right as you assigned them in the geometry and mesh) as in this figure below.
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 October 30, 2019, 08:14 #3 New Member   Ramy Join Date: Nov 2016 Posts: 5 Rep Power: 9 Please ignore the previous reply. The solution did not work out.