conjugate heat transfer, plz help

sepidehkavousi · July 16, 2012, 08:47

hi my dear friends
I am modeling a micro channel heat sink by FV method...my thermal boundary conditions for heat sink is adiabatic except for bottom wall which is constant heat flux.
I used ghost cells and ta the interface and for ghost cells for solid I reached the equation using continuity of fluxes at interface and for gost cells of fluid I used continuity of temprature but when I solve temprature of solid and fluid does not change much by the heat flux that is meant...I don't know if I did some thing wrong...plz help

Rami · July 23, 2012, 07:17

There is no need for ghost cells in weak formulation methods like the FEM and the FVM. In these methods - by application of the divergence theorem - the BCs are treated by the appropriate terms at the boundaries (e.g, the div(q) term in the FVM is given as integral over the cell surface of the normal flux, which is given as natural BC on the boundaries).

Rami · August 16, 2012, 06:46

Quote:

Originally Posted by sepidehkavousi

hi my dear friends
I am modeling a micro channel heat sink by FV method...my thermal boundary conditions for heat sink is adiabatic except for bottom wall which is constant heat flux.
I used ghost cells and ta the interface and for ghost cells for solid I reached the equation using continuity of fluxes at interface and for gost cells of fluid I used continuity of temprature but when I solve temprature of solid and fluid does not change much by the heat flux that is meant...I don't know if I did some thing wrong...plz help

Quote:

Originally Posted by Rami

There is no need for ghost cells in weak formulation methods like the FEM and the FVM. In these methods - by application of the divergence theorem - the BCs are treated by the appropriate terms at the boundaries (e.g, the div(q) term in the FVM is given as integral over the cell surface of the normal flux, which is given as natural BC on the boundaries).

dear rami
I do not under stand what to do in BC. I should pay attention to cnvergance of fluxes at boundaries, but I do not know what to do. to cells near boundary what should I do?
I wuld be very happy if you help me
thanks my friend

Please post or drop me an e-mail with the geometry, the solved equations, the heat sink and the BCs you wish to solve, and I'll try to help you.

July 16, 2012, 08:47	conjugate heat transfer, plz help	#1
sepidehkavousi New Member maryam Join Date: Jan 2012 Posts: 11 Rep Power: 14	hi my dear friends I am modeling a micro channel heat sink by FV method...my thermal boundary conditions for heat sink is adiabatic except for bottom wall which is constant heat flux. I used ghost cells and ta the interface and for ghost cells for solid I reached the equation using continuity of fluxes at interface and for gost cells of fluid I used continuity of temprature but when I solve temprature of solid and fluid does not change much by the heat flux that is meant...I don't know if I did some thing wrong...plz help

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July 23, 2012, 07:17		#2
Rami Senior Member Rami Ben-Zvi Join Date: Mar 2009 Posts: 155 Rep Power: 17	There is no need for ghost cells in weak formulation methods like the FEM and the FVM. In these methods - by application of the divergence theorem - the BCs are treated by the appropriate terms at the boundaries (e.g, the div(q) term in the FVM is given as integral over the cell surface of the normal flux, which is given as natural BC on the boundaries).