Fluent Laminar Natural convection

alpcfd · July 10, 2020, 07:45

Hello all, I am doing exercise to improve my CFD skills. I want to ask a question. My boundary conditions; bottom wall hot, top wall cold and side walls adiabatic. My material is air and set as Boussinesq.My temperature difference is 10 and Ra=10^5. My analysis (left picture) as you see rotates counterclockwise but the other picture which has the same conditions (Boundary conditions, Rayleigh Number, Material as air ) except the geometry shape but it is not big deal, the picture(right) spreads from the middle of the bottom wall. What is the reason for this?

I used default SIMPLE Method also I tried different methods like Coupled PISO etc. and I opened the specified operating density then closed but there didn't any changing.

rupak504 · July 10, 2020, 15:23

What about the surface tension

alpcfd · July 10, 2020, 15:59

Quote:

Originally Posted by rupak504

What about the surface tension

Thank you for your interest but actually, I have no idea about surface tension. There is not a specific description about surface tension and also this is single phase.So I think the surface tension is default or not open right now because I didn't anything and I am new at CFD. Can you a little bit explain then I can look at my work and say to you.

Best regards, Alp

karachun · July 10, 2020, 17:21

rupak504 but surface tension is multiphase only thing.

alpcfd maybe flow pattern depend from initial conditions and both variants are possible.
The easiest thing you can do is to model only half of domain - use symmetry.

July 10, 2020, 07:45	Fluent Laminar Natural convection	#1
alpcfd New Member amiraladama Join Date: May 2020 Posts: 13 Rep Power: 5	Hello all, I am doing exercise to improve my CFD skills. I want to ask a question. My boundary conditions; bottom wall hot, top wall cold and side walls adiabatic. My material is air and set as Boussinesq.My temperature difference is 10 and Ra=10^5. My analysis (left picture) as you see rotates counterclockwise but the other picture which has the same conditions (Boundary conditions, Rayleigh Number, Material as air ) except the geometry shape but it is not big deal, the picture(right) spreads from the middle of the bottom wall. What is the reason for this? I used default SIMPLE Method also I tried different methods like Coupled PISO etc. and I opened the specified operating density then closed but there didn't any changing.

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July 10, 2020, 15:23		#2
rupak504 Senior Member Lolita Join Date: Aug 2016 Posts: 115 Rep Power: 9	What about the surface tension

July 10, 2020, 17:21		#4
karachun Senior Member Join Date: Nov 2015 Posts: 244 Rep Power: 11	rupak504 but surface tension is multiphase only thing. alpcfd maybe flow pattern depend from initial conditions and both variants are possible. The easiest thing you can do is to model only half of domain - use symmetry.