Fluids

Conjugate heat transfer

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• ssshivam
Subscriber

I am doing Jet impingement heat transfer phenomenon on a solid plate in 2D. Solid plate is at 500K initially. Now from air jet impingement, it will cool down the Solid target plate.

I am initializing solid plate using patch option. I am running steady sate phenomenon. The problem here is I am not able to observe temperature variations in solid domain. However there is temperature variation along interface in fluid region only.

I need to see temperature variation in solid plate to do structural analysis. Interface is automatically selected as "Coupled" for both wall and its shadow. Please help.

• Rob
Ansys Employee

Have you created a multibody part (DesignModeler) or used Share Topology (SpaceClaim)?  It sounds like the two volumes aren't passing information.

• ssshivam
Subscriber

Yes sir, I have created two domains, one is fluid and one is solid. Then I combined them and form a one part.

• Rob
Ansys Employee

Now check boundary conditions. In steady state what is stopping the whole domain dropping/increasing to the air temperature?

• ssshivam
Subscriber

Sir, in steady state, the temperature of entire domain (both fluid and solid) is reduced to fluid temperature. Is it what supposed to happen as I believe at infinity, the temperature of solid will reach to fluid temperature?

• Rob
Ansys Employee

Yes, steady state is the equilibrium condition. If you want to look at the cool down you need a transient solution.

• ssshivam
Subscriber

Ty sir, I have solved the problem for this convection using transient solution. Now I need to apply CHF boiling model for because of film boiling on solid surface. Please suggest me the further approach as everytime I run my solution, errors do appear.

Its a 3 phase flow. In fluid domain air is there, Water will come from inlet, further as water fall on solid, film boiling occurs and vapors are form (3 phases : air, water and vapor). Now I am making assumption that air is same as vapor and reducing the problem to 2 phase flow. Now, Vapor is there is entire fluid domain and water enters from inlet. As water falls on heated solid, film boiling occurs and vapors are formed.

I am using by default boiling conditions (saturation temp = 373K) and setting my residual monitor when water facet maximum temperature reaches 373K (as boiling will stop at this condition). Please help.

• Rob
Ansys Employee

You can create a phase which comprises a species mixture: ie air & vapour.   What errors are you seeing?

• ssshivam
Subscriber

Sir, my solid domain(which is a thin plate) is moving with velocity=10m/s in above mentioned Jet impingement problem. I am initializing my solid domain with 800 kelvin using patch option. Vapors were visible initially(before 1 sec), but after that there are no vapors (may be because temp is reduced)

I want my incoming moving domain to be at 800K, but I think fluent is updating cooled temperature for incoming solid domain because of which vapors aren't visible.

• Rob
Ansys Employee

What did you set the solid temperature at on the boundary?  You may need to revise the extent of the domain if you're moving the solid zone.

• ssshivam
Subscriber

Sir, I have solved that problem, I was using symmetric condition which was causing problem as the flow wont be symmetric anymore for moving domain. As a further progress, I have implemented the boiling model successfully too.

Now, I am stuck with a new problem, which is: I have used coupled condition on the vertical solid walls. I want to use the simulated temperature values at outlet wall as the inlet temperature wall values as a next part of this problem. Geometry is same. Please suggest how to proceed.