Convergence issues for Wavy walled cavity filled with nanofluid

clfurness · February 15, 2017, 14:31

Hi everyone,
I have a cavity defined by a left and right vertical wall, joined by two wavy horizontal walls.
I am manipulating Rayleigh number by changing 'g' and keeping the temperature difference as 1 k.
The vertical walls are adiabatic. The top wall is at 293 k and the bottom wall is at 294 k. This creates natural convection in the fluid, given that the change in temperature changes the density of the fluid, and so the the boussinesq model is used.

i have tried changing the relaxation factors using trial and error and not had a single simulation converge.

I have tried using a lower Rayleigh number and a courser mesh to try and get convergence on a 'simplified' model first, and re-solve again and again as i increase the rayleigh number and mesh back to the desired values.

I have these problems on both ANSYS 15.0 accademic and ANSYS student 17.2.

Can anyone help?

ali_reza · September 3, 2017, 16:40

Hi

try manipulating Rayleigh number by changing Thermal expansion coefficient.

Regards

February 15, 2017, 14:31	Convergence issues for Wavy walled cavity filled with nanofluid	#1
clfurness New Member Connor Furness Join Date: Feb 2017 Posts: 1 Rep Power: 0	Hi everyone, I have a cavity defined by a left and right vertical wall, joined by two wavy horizontal walls. I am manipulating Rayleigh number by changing 'g' and keeping the temperature difference as 1 k. The vertical walls are adiabatic. The top wall is at 293 k and the bottom wall is at 294 k. This creates natural convection in the fluid, given that the change in temperature changes the density of the fluid, and so the the boussinesq model is used. i have tried changing the relaxation factors using trial and error and not had a single simulation converge. I have tried using a lower Rayleigh number and a courser mesh to try and get convergence on a 'simplified' model first, and re-solve again and again as i increase the rayleigh number and mesh back to the desired values. I have these problems on both ANSYS 15.0 accademic and ANSYS student 17.2. Can anyone help?

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September 3, 2017, 16:40		#2
ali_reza New Member alireza keyhani Join Date: Feb 2017 Posts: 4 Rep Power: 9	Hi try manipulating Rayleigh number by changing Thermal expansion coefficient. Regards