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-   -   Turbulent natural convection (https://www.cfd-online.com/Forums/fluent/187690-turbulent-natural-convection.html)

JuanDCS May 12, 2017 16:08

Turbulent natural convection
 
Hi guys, im doing simulations of free convection over heat spheres in high Rayleigh numbers, the thing its that when i use some turbulent model the heat goes up, im focusing in use low reynolds number models, and still heat its high, so what you guys can advice me to do? so i can get betters results

JuanDCS June 8, 2017 13:07

Hi guys,
I change the limit viscosity ratio to values lower than 1000 and the results of heat transfer were good, but the residuals dont converge to the value i set, this dont down more that 1e-03, what can be the problem and how i do to get my converge criteria?

JuanDCS June 15, 2017 20:12

Initialization of low-re-ke
 
Hi guys,
I've been doing some modifications to my simulation, the sphere that i have been simulating its in a box with temperature of 298 K, the sphere have 308 K and the top its a free surface, i have the top as pressure outlet, when i use the turbulence model (Abe-Kondoh-Nagano) appear the advertising of turbulence viscosity ratio to xx cells, when i modified the values of turbulent kinetic dissipation and turbulent dissipation rate in the initialization, the simulation solve the flow very well, but i dont know if the modification of this value its alright? will appreciate the help its for my degree work


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