Using ideal gas law and sutherland law in Fluent

RyGuy · July 27, 2009, 15:12

Hello Fluent Users,

I am working on a project regarding the simulation of a process called Low Pressure Cold Spray (also known as Kinetic Spray). I am trying to analyze theoretically the single and multi-phase flow of the process and compare it with experimental data.

Therefore I have created my geometry in Gambit (simple 2d geometry of a convergent-divergent nozzle) and meshed the geometry with quad cells.

I have exported the mesh into Fluent and due to the nature of the process the procedure for setting up the simulation is as follows:

I defined the process using the density based implicit solver, 2D, Steady time enabling the energy equation for thermal considerations. I have selected the k-epsilon standard model and am only considering a single phase supersonic compressible flow. I am using an operating pressure of zero since mach number is greater than 0.1

I have found from literature that it would be ideal to consider the ideal-gas law for the material properties (air) and also the sutherland viscosity law for better accuracy in terms of compressibility and viscous effects.

My main inlet pressure and temperature ranges are 5-10 bars and 500-1000 K, respectively.

When I try to incorporate the ideal gas las for density of air and iterate to get a solution Fluent gives me an Error: floating point error and Error: Object () prompt.

How do I avoid this error? And, if anyone who fully understands Fluent can optimize my procedure for this process can you please provide your input?

Your replies are greatly anticipated....
Thanks in advance!

Ryan

Chris D · July 29, 2009, 20:35

Have you tried this? (See 2.1.1)

http://www.cfd-online.com/Wiki/Fluent_FAQ

I had a floating point error today, and reducing the Courant number solved the problem for me.

RyGuy · July 30, 2009, 11:04

Hello Chris,

Sorry I am new to this forum and have not been able to check out the FAQ.
I will give it a try and will keep you posted if it is successful or not.

Thanks for everything,
Ryan

Tpozkar · June 12, 2012, 15:38

Hi RyGuy, I would like if you resolved your problem. I have a similar problem

I´m trying to simulate a compressible flow in a gas turbine, and I get the following error:

Error: Internal error at line 1387 in file '..\..\src\rp_mstage.c'.
Divergence detected in AMG solver

I have tried the suggestions of the fluent_FAQ but I´m not able to resolve my problem.

regards

fuxiao_20 · June 28, 2012, 03:07

you can try intialize the flow field with a slow speed

July 27, 2009, 15:12	Using ideal gas law and sutherland law in Fluent	#1
RyGuy New Member Ryan Join Date: Jul 2009 Location: Windsor Posts: 9 Rep Power: 17	Hello Fluent Users, I am working on a project regarding the simulation of a process called Low Pressure Cold Spray (also known as Kinetic Spray). I am trying to analyze theoretically the single and multi-phase flow of the process and compare it with experimental data. Therefore I have created my geometry in Gambit (simple 2d geometry of a convergent-divergent nozzle) and meshed the geometry with quad cells. I have exported the mesh into Fluent and due to the nature of the process the procedure for setting up the simulation is as follows: I defined the process using the density based implicit solver, 2D, Steady time enabling the energy equation for thermal considerations. I have selected the k-epsilon standard model and am only considering a single phase supersonic compressible flow. I am using an operating pressure of zero since mach number is greater than 0.1 I have found from literature that it would be ideal to consider the ideal-gas law for the material properties (air) and also the sutherland viscosity law for better accuracy in terms of compressibility and viscous effects. My main inlet pressure and temperature ranges are 5-10 bars and 500-1000 K, respectively. When I try to incorporate the ideal gas las for density of air and iterate to get a solution Fluent gives me an Error: floating point error and Error: Object () prompt. How do I avoid this error? And, if anyone who fully understands Fluent can optimize my procedure for this process can you please provide your input? Your replies are greatly anticipated.... Thanks in advance! Ryan

July 29, 2009, 20:35		#2
Chris D Senior Member Chris Join Date: Jul 2009 Location: Ohio, USA Posts: 169 Rep Power: 17	Have you tried this? (See 2.1.1) http://www.cfd-online.com/Wiki/Fluent_FAQ I had a floating point error today, and reducing the Courant number solved the problem for me.

July 30, 2009, 11:04		#3
RyGuy New Member Ryan Join Date: Jul 2009 Location: Windsor Posts: 9 Rep Power: 17	Hello Chris, Sorry I am new to this forum and have not been able to check out the FAQ. I will give it a try and will keep you posted if it is successful or not. Thanks for everything, Ryan

June 12, 2012, 15:38		#4
Tpozkar New Member Tpozkar Join Date: Jan 2012 Location: Mexico Posts: 4 Rep Power: 14	Hi RyGuy, I would like if you resolved your problem. I have a similar problem I´m trying to simulate a compressible flow in a gas turbine, and I get the following error: Error: Internal error at line 1387 in file '..\..\src\rp_mstage.c'. Divergence detected in AMG solver I have tried the suggestions of the fluent_FAQ but I´m not able to resolve my problem. regards

June 28, 2012, 03:07		#5
fuxiao_20 New Member fuxiao Join Date: Jun 2012 Posts: 2 Rep Power: 0	you can try intialize the flow field with a slow speed