# Cylinderical coordinate

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 June 9, 2004, 03:48 Cylinderical coordinate #1 Avesta Guest   Posts: n/a Sponsored Links 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?

 June 9, 2004, 10:34 Re: Cylinderical coordinate #2 ozgur Guest   Posts: n/a Hi, You have to use axisymmetric solver with rectangular domain, since you have rotational symmetry in your problem.

 June 12, 2004, 08:47 Re: Cylinderical coordinate #3 Avesta Guest   Posts: n/a hi dear thanks much but in fluent there are not axisymmetric solver. there are axis and symmetric apartly.

 June 13, 2004, 15:59 Re: Cylinderical coordinate #4 Arun Guest   Posts: n/a 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

 June 17, 2004, 06:56 Re: Cylinderical coordinate #5 Avesta Guest   Posts: n/a 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

 June 17, 2004, 10:57 Re: Cylinderical coordinate #6 Arun Guest   Posts: n/a 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

 June 18, 2004, 06:13 Re: Cylinderical coordinate #7 Avesta Guest   Posts: n/a hi thank you ok in grid check appear negative volumes. how do i change these negative volumes to positive volumes ? best regard byeeeee

 June 18, 2004, 12:24 Re: Cylinderical coordinate #8 Arun Guest   Posts: n/a 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

 June 19, 2004, 06:36 Re: Cylinderical coordinate #9 Avesta Guest   Posts: n/a hi thank you i use from GAMBIT guide me best regard Avesta

 June 22, 2004, 09:28 Re: Cylinderical coordinate #10 ozgur Guest   Posts: n/a Hi, When using axsy. solver, x-axis should be you axis of symmetry. Is that so in your case?

 June 27, 2004, 02:38 Re: Cylinderical coordinate #11 avesta Guest   Posts: n/a hi thank you best regard avesta

 June 27, 2004, 03:30 Re: Cylinderical coordinate #12 avesta Guest   Posts: n/a 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

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