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Coupling time dependent heat transer with stationary flow

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Hello all,

I want to run a stationary simulation to calculate the turbulent flow in a pipe. Afterwards, I want to simulate the heating up process. So I run a 10 seconds time dependent simulation.

Until here, everything works fine.

My Problem: I Insert a mass flow. When the temperature increases, the density get lower, so the velocity increases.

To reduce the error, I run a second stationary study step, where the velocity is based on the new temperature. But the new velocity is still calculated with the initial density, not with a new one.

Set-up:

Flow: SST, weakly compressible Heat Transer physics Non Isothermal flow Multiphysics

Tried constellations: -Deaktivating the Multiphysics while solving the flow: spf.rho stays constant

Enabling the Multiphysics: While solving the second stationary flow study: Error: Undefined variable. - Variable: CFLCMP

Setting the SST equation from study controlled to stationary: While solving the second flow study: Error: Undefined variable. - Variable: timestept

Disabling the pseudo Time Stepping: Undefined variable. - Variable: timestep

Has someone an idea how to calculate the new flow with the lower density? :-)

Thanks!

Henrik Bode


0 Replies Last Post 19.06.2018, 11:04 GMT-4
COMSOL Moderator

Hello Henrik Bode

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