hi all in cylinderical coordinate if there are not variation in teta direction ,may it simulate and compute heat transfer and Nusselt number of a tube with a 2dimentional model as rectangular?

Hi,

You have to use axisymmetric solver with rectangular domain, since you have rotational symmetry in your problem.

hi dear thanks much but in fluent there are not axisymmetric solver. there are axis and symmetric apartly.

Hi

In Define->Models->Solver, you have an option of axisymmetric in "space". You have to define the symmetry edge as axis if you want to do axisymmetric calculation.

Arun

hi thank you when i define axisymmetry this error appear: Error: divergence detected in AMG solver: x-momentum Error Object: () please guide me best regard Avesta

Hi

Did you do a grid check first? If you have negative volumes this error occurs. There may be other reasons but try this first.

Thanks Arun

hi thank you ok in grid check appear negative volumes. how do i change these negative volumes to positive volumes ? best regard byeeeee

Hi

which grid generation software are u using? Make sure that your grid does not have intersecting grid lines. If it does, then you need to redo the grid properly.

Arun

hi thank you i use from GAMBIT guide me best regard Avesta

Hi,

When using axsy. solver, x-axis should be you axis of symmetry. Is that so in your case?

hi thank you best regard avesta

hi all All books on heat transfer tell me the Nusselt number of the fully-developed laminar flow in a pipes is a constant;if the wall temperature is constant,the Nu=3.66;if the heat flux is constant,the Nu will be 4.36. but when i simulate this ,Nu in constant wall temperature will be 2.59 and it do not limit to 3.66 in fully developed laminar flow. i do not know what reference values put in meno of reference valuen in report>reference values... what reference values do you recommand? i want to simulate laminar flow in a pipe as non-dimentional by Fluent? inflow: U=1,T=1 WALL: U=0, T=1 Density=1, Cp=1, Thermal Conductivity(K)=1/(Re.Pr), Viscosity=1/Re guide me best regard Avesta