CHT problem

mobiuspizza · March 17, 2016, 10:09

Sorry I am new to CFD I hope what I ask makes sense

I wanted to model natural convection for a thin plate object suspended in a fluid in an enclosed volume. The solid has a higher initial temperature.

I have imprinted the fluid and the object and created a solid-fluid interface. The mesh is conformal with percentages at 98% for master and slave.

I am confused as to what to put in at the Region\Solid\boundary\wall-touching-fluid
physical conditions\thermal specification, am I suppose to put Convective?
What about the Region\Fluid\boundary\wall-touching-solid
physical conditions\thermal specification ? It is defaulted to adiabatic.

When I set both to adiabatic, the fluid never moves and there is no convention (plotting velocity vectors show up as empty). I guess that is modelling pure conduction if I do that.

Should I put convective then if so which boundary? Fluid side or solid side? If I do that it asks for the heat transfer coefficient. Surely that's the output of the simulation, I wouldn't have a clue what it is suppose to be.

Many thanks

LeeTao · March 21, 2016, 23:25

Hello, mobiuspizza

I think I can understand what you mean.

If you want to simulate convection, use the ideal gas model with Energy model, then the fluid density will change with temperature and pressure, then you can see the convection flow.

Here is my suggestion.

Leetao

kguntur · March 22, 2016, 00:23

Yes. You need to model the gas as anything other than constant density. Also, dont forget to select gravity as well.

March 17, 2016, 10:09	CHT problem	#1
mobiuspizza New Member Join Date: Mar 2016 Posts: 1 Rep Power: 0	Sorry I am new to CFD I hope what I ask makes sense I wanted to model natural convection for a thin plate object suspended in a fluid in an enclosed volume. The solid has a higher initial temperature. I have imprinted the fluid and the object and created a solid-fluid interface. The mesh is conformal with percentages at 98% for master and slave. I am confused as to what to put in at the Region\Solid\boundary\wall-touching-fluid physical conditions\thermal specification, am I suppose to put Convective? What about the Region\Fluid\boundary\wall-touching-solid physical conditions\thermal specification ? It is defaulted to adiabatic. When I set both to adiabatic, the fluid never moves and there is no convention (plotting velocity vectors show up as empty). I guess that is modelling pure conduction if I do that. Should I put convective then if so which boundary? Fluid side or solid side? If I do that it asks for the heat transfer coefficient. Surely that's the output of the simulation, I wouldn't have a clue what it is suppose to be. Many thanks

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March 21, 2016, 23:25		#2
LeeTao New Member LeeTao Join Date: Nov 2015 Posts: 3 Rep Power: 10	Hello, mobiuspizza I think I can understand what you mean. If you want to simulate convection, use the ideal gas model with Energy model, then the fluid density will change with temperature and pressure, then you can see the convection flow. Here is my suggestion. Leetao

March 22, 2016, 00:23		#3
kguntur Member kris Join Date: May 2014 Posts: 73 Rep Power: 12	Yes. You need to model the gas as anything other than constant density. Also, dont forget to select gravity as well.