|
[Sponsors] |
March 17, 2015, 05:41 |
Simple Flow Problem
|
#1 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
hey guys need help in solving this question. I did attach a pic to see overview of question.
Here's the detail i put while solving this question: SOLVER TYPE : Pressure Based Velocity Formulation : Absolute Time : Steady MODEL : Laminar MATERIAL : Water<Liquid> BOUNDARY CONDITION : INLET- velocity magnitude = 1 m/s gauge pressure = 100000 Pa OUTLET - gauge pressure = 100100 Pa **Rest are walls with default setting. REFERENCE VALUE : COMPUTE from Inlet SOLUTION CONTROL : pressure = 0.2 momentum = 0.6 ***HYBRID INITIALIZATION And Here's the result i am getting : - After Initialization : Setting Post Processing and Surfaces information ... Done. /solve/initialize/hyb-initialization Initialize using the hybrid initialization method. Checking case topology... -this case has inlets & outlets both -pressure information is not available at the boundaries, so it will be initialized with constant pressure iter scalar-0 1 1.000000e+00 2 6.955973e-05 3 1.515677e-05 4 1.302184e-05 5 1.477042e-05 6 7.976428e-06 7 8.482481e-06 8 9.215501e-06 9 6.680556e-06 10 8.885878e-06 hybrid initialization is done. Warning: convergence tolerance of 1.000000e-06 not reached during Hybrid Initialization. -Divergence detected in AMG solver: pressure correction -# Divergence detected in AMG solver: pressure correction -> Turning off correction scaling! -# Divergence detected in AMG solver: pressure correction -> Turning off correction scaling! |
|
March 17, 2015, 06:31 |
|
#2 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
Is ur gauge pressure is atmospheric pressure
|
|
March 17, 2015, 06:35 |
|
#3 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
yes it is atmospheric pressure..
|
|
March 17, 2015, 06:36 |
|
#4 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
Then set ur gauge pressure to zero.
|
|
March 17, 2015, 06:38 |
|
#5 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
Both inlet and outlet
|
|
March 17, 2015, 06:50 |
Inlet and Outlet gauge pressure = 0 Pa
|
#6 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
Initialize using the hybrid initialization method.
Checking case topology... -this case has inlets & outlets both -pressure information is not available at the boundaries, so it will be initialized with constant pressure iter scalar-0 1 1.000000e+00 2 6.945340e-05 3 1.450468e-05 4 1.625007e-05 5 1.728765e-05 6 1.128941e-05 7 8.551013e-06 8 8.563514e-06 9 1.146841e-05 10 7.437878e-06 hybrid initialization is done. Warning: convergence tolerance of 1.000000e-06 not reached during Hybrid Initialization. Writing Settings file... writing rp variables ... Done. writing domain variables ... Done. writing fluid (type fluid) (mixture) ... Done. writing l-outlet (type pressure-outlet) (mixture) ... Done. writing l-inlet (type velocity-inlet) (mixture) ... Done. writing int_fluid (type interior) (mixture) ... Done. writing l-back (type wall) (mixture) ... Done. writing l-bottom (type wall) (mixture) ... Done. writing l-front (type wall) (mixture) ... Done. writing l-top (type wall) (mixture) ... Done. writing s1-bottom (type wall) (mixture) ... Done. writing s2-top (type wall) (mixture) ... Done. writing zones map name-id ... Done iter continuity x-velocity y-velocity z-velocity time/iter 1 1.0000e+00 6.4548e-03 2.8059e-01 1.2227e-03 0:33:18 999 2 1.0000e+00 3.6747e-01 1.6220e+01 6.2894e-03 0:33:16 998 3 1.2984e-01 3.3730e-03 5.3236e-01 3.7364e-03 0:36:33 997 # Divergence detected in AMG solver: pressure correction -> Turning off correction scaling! 4 1.0000e+00 2.0753e-01 2.4740e+01 2.8992e-03 0:39:11 996 5 2.8992e-01 2.1585e-02 6.4564e-01 2.2856e-02 0:41:16 995 6 2.6850e+00 7.2350e-02 5.5865e-01 6.9776e-02 0:42:55 994 # Divergence detected in AMG solver: pressure correction -> Increasing relaxation sweeps! Error: Divergence detected in AMG solver: pressure correction Error Object: #f |
|
March 17, 2015, 07:29 |
|
#7 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
Is ur simulation is 3D or 2D
|
|
March 17, 2015, 07:42 |
|
#8 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
Its 3D , With thickness of 1mm
|
|
March 17, 2015, 07:46 |
|
#9 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
Whats ur solution method details??
|
|
March 17, 2015, 08:19 |
|
#10 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
Solution method is SIMPLC with default setting of other parameter under that.
|
|
March 17, 2015, 08:30 |
|
#11 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
use SIMPLE as pressure velocity coupling
|
|
March 17, 2015, 11:12 |
|
#12 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
What turbulence model u have been using
|
|
March 18, 2015, 00:18 |
|
#13 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
Turbulence model is Laminar.
And still i am not getting converge solution with any of the solver. Btw i have one more doubt : Why is it when we bring a mesh file from ICEM to FLUENT its quality degraded??? |
|
March 18, 2015, 01:18 |
|
#14 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
Due to fluent accepts only unstructured mesh. Use k- epsilon model for ur flow
|
|
March 18, 2015, 01:22 |
|
#15 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
I have used k-epsilion model as well. It didn't work.
Btw then what is the solution for my mesh. How can i call my structured mesh to fluent without affecting its quality. Btw does high aspect ratio effect the solution in my case. |
|
March 18, 2015, 01:44 |
|
#16 |
New Member
Muthu pandy
Join Date: Feb 2015
Posts: 20
Rep Power: 11 |
Select ur output solver as fluent. Before that convert ur premesh to unstructured mesh.
Aspect ratio must be close to 1 shows high quality. 0 shows low quality. |
|
March 18, 2015, 05:15 |
|
#17 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
I am sorry but how aspect ratio can be less than 1. Its maximum side/minimum side.
|
|
March 18, 2015, 10:41 |
|
#18 |
Senior Member
Rick
Join Date: Oct 2010
Posts: 1,016
Rep Power: 27 |
Simple flow? I think no...
You have an inlet velocity of 1 m/s with a cross area of 10,001mm x 1mm. Then the fluid should pass in a restriction of about 0,001mm x 1mm: approximately your fluid will reach a velocity of 10000 m/s!!!! Are you sure of your boundary conditions? Even with low inlet velocity you should expect also cavitation.
__________________
Google is your friend and the same for the search button! Last edited by ghost82; March 18, 2015 at 12:09. |
|
March 18, 2015, 11:56 |
|
#19 |
New Member
Shailesh
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
I know cavitation is suppose to happen there. But still how can solve this situation???
What changes should i bring to my boundary condition or any other conditions to get the final results. Btw can you also explain me how cavitation is affecting my result???(if you think it is) |
|
March 18, 2015, 12:05 |
|
#20 |
Senior Member
Rick
Join Date: Oct 2010
Posts: 1,016
Rep Power: 27 |
The problem here is not cavitation.
How did you set your inlet velocity? From experimental or..? It's non physical to have 10000 m/s velocity in the restriction..Try to solve for Bernoulli and you will notice that you need to have a non physical pressure inlet...
__________________
Google is your friend and the same for the search button! |
|
Tags |
ansys, ansys 14, fluent, fluent 14 |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Domain format problem on airfoil flow simulation | andrenonaka | CFX | 14 | December 7, 2015 01:42 |
Problem with changing mass flow rate | roo | FLUENT | 3 | June 4, 2013 15:53 |
Problem of mass conservation in multispecies flow in porous media and T° gradient | pilou | FLUENT | 0 | January 31, 2011 09:19 |
Can 'shock waves' occur in viscous fluid flows? | diaw | Main CFD Forum | 104 | February 16, 2006 06:44 |
Multiphase flow problem | icedou | FLUENT | 6 | July 10, 2005 03:52 |