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Turbulent Flow Model

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I have a very simple 2D flow model. It is to simulate flow through straight pipe. The model solve in ~3 minutes when I solve for laminar flow using air with and inlet flow of u_mean*6*s*(1-s)*step1(t[1/s]) and an outlet boundary condition of 0 pressure. When I switch the model to turbulent flow (which is what we actually have) the model takes significantly longer to solve. Anyone have any tips on improving the speed for solution time?

Thanks.

1 Reply Last Post 29.11.2011, 01:43 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 29.11.2011, 01:43 GMT-5
Hi

turbulence is tricky to model so it takes the solver several iterations to get there, but, normally you can gain time by using good initial conditions, and ensure your meshing is adequate, I often run a laminar case to initiate velocity and pressures, then I try the turbulence model starting from the previous calculated values, this is often also done by default in COMSOL for the new solver settings. Anyhow such complex simulations require quite some experience, that comes only by making many models and learn there from. I'm not a specialist in CFD, there are for more experiences persons out here on the FORUM that might come with better tips ;)

--
Good luck
Ivar
Hi turbulence is tricky to model so it takes the solver several iterations to get there, but, normally you can gain time by using good initial conditions, and ensure your meshing is adequate, I often run a laminar case to initiate velocity and pressures, then I try the turbulence model starting from the previous calculated values, this is often also done by default in COMSOL for the new solver settings. Anyhow such complex simulations require quite some experience, that comes only by making many models and learn there from. I'm not a specialist in CFD, there are for more experiences persons out here on the FORUM that might come with better tips ;) -- Good luck Ivar

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