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Pressure and velocity between two plates with rising temperature

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Old   February 25, 2019, 11:13
Default Pressure and velocity between two plates with rising temperature
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Amah Atungsiri
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Hi,

I'm currently trying to model flow between two plates. The model is 2D. There is heat flux on the top plate and I want to see the effect heating has on the fluid parameters.

Gravity is applied, adjusted as the system is tilted.

I have an arbitrary level of 1500 W/m^2 of heat flux on the top plate.
The fluid is air, flowing in at 0.03 m/s with a temperature of 33.5 degrees.

The flow is transient, flowing for 50s with 20 iterations in each time step with a step size of 1s. I initially ran it for a steady state analysis but my transient solution matches the results so I'v opted to use that.

Inflation layers have been added to resolve the boundary layer although the flow is laminar.

My issue is that the temperature rise from the heat flux has no effect on the velocity and pressure plots even though it reaches max values of 2000 degrees. The gravity also has no effect on the results.

Is there a function in my fluid setup that I'm missing?

Any help would be appreciated thanks.
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File Type: png temp.PNG (26.8 KB, 6 views)
File Type: png press.PNG (34.3 KB, 6 views)
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Old   February 25, 2019, 13:05
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Go to material properties and check your equation of state for density.
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Old   February 26, 2019, 11:52
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Amah Atungsiri
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Thanks for the reply.

My density was set as constant so I changed it to ideal-gas (not sure if this is the correct equation of state).

The plots produced a lot of vortexes caused by the reversed flow I had at my pressure outlet.

My understanding is that the fluid should heat up as it enters the domain so that the outlet pressure is higher than the inlet.

I chose incompressible ideal gas because I understand that fluid density will only depend on temperature. The information I found says Boussinesq is for buoyancy driven flow, and real gas equations are for flow conditions which don't follow ideal flow.

Its likely the BC cause the reversed flow but I'm not sure how to change them since I don't know the pressure at the outlet.

Any guidance on the reversed flow would be appreciated.
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Old   February 26, 2019, 16:04
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A 0 pressure outlet should give a result, even if it's not the one you are imagining.


Just play with your case. Happy debugging.
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