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March 30, 2009, 19:58 |
BC in closed box simulation
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#1 |
New Member
Miguel Baritto
Join Date: Mar 2009
Location: Caracas,Venezuela
Posts: 16
Rep Power: 17 |
Hi,
I am simulating free convection inside a closed box. I have set heat flux at the bottom and insulated walls at the others surfaces. Also, I have set no slip at all the surfaces. However, I have problems with convergence and I think (after read cfx documentation) they are in BCs, since I haven't set pressure nor temperature levels at any BC. Could this be true? if so, how can I set pressure and temperature in a closed and insulated box? Thanks Miguel |
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March 31, 2009, 17:55 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,716
Rep Power: 143 |
Hi,
I assume you are running a transient simulation - it has to be as you have a hot wall on the bottom and everything else adiabatic so it is going to heat up over time. These type of buoyancy simulations invariably have big transient flow instabilities. You often have to run much smaller timesteps than you would expect to resolve these transient features. Just set the reference pressure and temperature at the initial temp and pressure, that should be OK. Glenn Horrocks |
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March 31, 2009, 20:16 |
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#3 |
New Member
Miguel Baritto
Join Date: Mar 2009
Location: Caracas,Venezuela
Posts: 16
Rep Power: 17 |
Thanks Glenn,
I will try smaller timesteps. |
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