Navier-Stokes Solver
Navier-Stokes Solver
Dear Elmer group
Hi
I’m working on a very simple axisymmetric model of tube with Navier-Stokes Solver.
I apply pressure=5000 pa in the inlet and pressure=0 pa in the outlet.
While the case seems really simple, it does not converge. Can you please help me solve this problem?
Thanks, Hamed
Hi
I’m working on a very simple axisymmetric model of tube with Navier-Stokes Solver.
I apply pressure=5000 pa in the inlet and pressure=0 pa in the outlet.
While the case seems really simple, it does not converge. Can you please help me solve this problem?
Thanks, Hamed
Re: Navier-Stokes Solver
Hi Hamed,
I cannot help personally since I have never used the NS solver. But I think you should post your case here (mesh and sif files) in order to enable others with NS knowledge to have a look at it.
Matthias
I cannot help personally since I have never used the NS solver. But I think you should post your case here (mesh and sif files) in order to enable others with NS knowledge to have a look at it.
Matthias
Re: Navier-Stokes Solver
Hi Matthias
Here is the test case.
Thanks for your help, Hamed
Here is the test case.
Thanks for your help, Hamed
- Attachments
-
- ToELMER.rar
- (52.87 KiB) Downloaded 370 times
Re: Navier-Stokes Solver
Hi Hamed!
Thetr was no second velosity component given for inlet.
See code below
Thetr was no second velosity component given for inlet.
See code below
Code: Select all
Header
Mesh DB "." "TubeMesh"
End
Constants
End
Simulation
Coordinate System = Axi Symmetric
Simulation Type = Steady State
Steady State Max Iterations = 50
Steady State Min Iterations = 2
Output Intervals = 1
Post File = "Stenosis.ep"
End
Body 1
Equation = 1
Material = 1
End
Material 1
Density = 1000.0
Viscosity = 0.004
End
Solver 1
Equation = Navier-Stokes
Stabilize = True
Linear System Solver = Iterative
Linear System Iterative Method = BiCGStabl
Linear System Preconditioning = ILU1
Linear System Max Iterations = 500
Linear System Convergence Tolerance = 1.0e-8
Nonlinear System Max Iterations = 10
Nonlinear System Convergence Tolerance = 1.0e-5
Nonlinear System Newton After Tolerance = 1.0e-5
Nonlinear System Newton After Iterations = 20
Nonlinear System Relaxation Factor = 0.7
Steady State Convergence Tolerance = 1.0e-4
End
Equation 1
Active Solvers(1) = 1
End
! inlet
Boundary Condition 1
Target Boundaries = 1
Velocity 1 = 0
Velocity 2 = 1
Pressure = 5000.0
End
! outlet
Boundary Condition 2
Target Boundaries = 3
Velocity 1 = 0.0
Pressure = 0.0
End
! symmetriy
Boundary Condition 3
Target Boundaries = 4
Velocity 1 = 0.0
End
! Wall
Boundary Condition 4
Target Boundaries = 2
Velocity 1 = 0.0
Velocity 2 = 0.0
End
Re: Navier-Stokes Solver
Hi dmitry
Thanks for your comment. But the inlet velocity is not 1 or anything else prescribed. It's actually a part of solution.
I hope Peter read this post and help me.
Thanks, Hamed
Thanks for your comment. But the inlet velocity is not 1 or anything else prescribed. It's actually a part of solution.
I hope Peter read this post and help me.
Thanks, Hamed
Re: Navier-Stokes Solver
Hi Hamed,
I cannot open the attached .rar file in my Ubuntu 14.04 desktop. can you attach it in .gz version (so that it would be convenient for your targeted commenters)?
I am thankful to Dmitry for making the SIF file available on behalf of Hamed. Cheers.
Yours Sincerely,
Anil Kunwar
I cannot open the attached .rar file in my Ubuntu 14.04 desktop. can you attach it in .gz version (so that it would be convenient for your targeted commenters)?
I am thankful to Dmitry for making the SIF file available on behalf of Hamed. Cheers.
Yours Sincerely,
Anil Kunwar
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Re: Navier-Stokes Solver
Hi Anil
Thanks for your kind attention.
I attached the .tgz file.
Best regards, Hamed
Thanks for your kind attention.
I attached the .tgz file.
Best regards, Hamed
- Attachments
-
- ToELMER.tgz
- (59.47 KiB) Downloaded 378 times
Re: Navier-Stokes Solver
Hi Hamed,
Your convergence issue is defined as:
Observation:
i.) Your linear system convergence tolerance setting is 1.0e-8.
ii.)The solver failed to converge in the 270th iteration, when the tolerance jumped from 1.0e-6 (within tolerance) to 1.0e-38 (far smaller tolerance width than the set 1.0e-8).
I express herein my rough guesses:
1. Try changing Linear System Preconditioning tools from ILU1 to others.
2. What is the fineness of your axisymmetric meshes?
For more information, you can view the following posts:
viewtopic.php?f=3&t=3920&p=13729&hilit= ... 5be#p13729
viewtopic.php?f=3&t=3372&p=13061&hilit= ... 5be#p13061
Yours Sincerely
Anil Kunwar
Your convergence issue is defined as:
Code: Select all
IterSolver: Using iterative method: bicgstab
CRS_IncompleteLU: ILU(1) (Real), Starting Factorization:
CRS_IncompleteLU: ILU(1) (Real), NOF nonzeros: 81226
CRS_IncompleteLU: ILU(1) (Real), filling (%) : 137
CRS_IncompleteLU: ILU(1) (Real), Factorization ready at (s): 0.00
1 0.1124E+05
2 0.7514E+04
3 0.5889E+04
4 0.1708E+05
5 0.3866E+04
6 0.2429E+04
7 0.2580E+04
8 0.2275E+04
9 0.3035E+04
10 0.1031E+06
11 0.2049E+04
12 0.1822E+04
13 0.2328E+04
14 0.1327E+04
15 0.1211E+04
16 0.1222E+04
17 0.1139E+04
18 0.1130E+04
19 0.1147E+04
20 0.1106E+04
21 0.1089E+04
22 0.1182E+04
23 0.1358E+04
24 0.1402E+04
25 0.1570E+04
26 0.1381E+04
27 0.1409E+04
28 0.6168E+03
29 0.5025E+03
30 0.2913E+03
31 0.3302E+03
32 0.1333E+03
33 0.1059E+03
34 0.1962E+03
35 0.8856E+02
36 0.8878E+02
37 0.9958E+02
38 0.9659E+02
39 0.3875E+02
40 0.3510E+03
41 0.3105E+03
42 0.3118E+03
43 0.3135E+03
44 0.2634E+03
45 0.7139E+02
46 0.6194E+02
47 0.6374E+02
48 0.1161E+03
49 0.5760E+01
50 0.5687E+01
51 0.1241E+01
52 0.1185E+01
53 0.1287E+01
54 0.9660E-01
55 0.1075E+00
56 0.5053E-01
57 0.3380E-01
58 0.2505E-01
59 0.2436E-01
60 0.2422E-01
61 0.1878E-01
62 0.1883E-01
63 0.1655E+00
64 0.4446E-01
65 0.1493E-02
66 0.1373E-02
67 0.1298E-02
68 0.1621E-02
69 0.1719E-02
70 0.4436E-03
71 0.5970E-03
72 0.8140E-03
73 0.1712E-03
74 0.1372E-04
75 0.2752E-04
76 0.2608E-04
77 0.2598E-04
78 0.3635E-03
79 0.3873E-04
80 0.3631E-04
81 0.9381E-04
82 0.7828E-04
83 0.1010E-03
84 0.9913E-04
85 0.9599E-04
86 0.1026E-03
87 0.3557E-04
88 0.3782E-04
89 0.4027E-04
90 0.3586E-03
91 0.8586E-05
92 0.8552E-05
93 0.7416E-05
94 0.6277E-05
95 0.1689E-05
96 0.1410E-05
97 0.1916E-05
98 0.1727E-05
99 0.1453E-05
100 0.1964E-05
101 0.1968E-05
102 0.1677E-05
103 0.3624E-06
104 0.3147E-06
105 0.3398E-06
106 0.3393E-06
107 0.3394E-06
108 0.3979E-06
109 0.3284E-06
110 0.3265E-06
111 0.2866E-06
112 0.2866E-06
113 0.2835E-06
114 0.2844E-06
115 0.2838E-06
116 0.2838E-06
117 0.2838E-06
118 0.2838E-06
119 0.2838E-06
120 0.2838E-06
121 0.2838E-06
122 0.2838E-06
123 0.2838E-06
124 0.2838E-06
125 0.2838E-06
126 0.2838E-06
127 0.2838E-06
128 0.2838E-06
129 0.2838E-06
130 0.2838E-06
131 0.2838E-06
132 0.2838E-06
133 0.2838E-06
134 0.2838E-06
135 0.2838E-06
136 0.2838E-06
137 0.2838E-06
138 0.2838E-06
139 0.2838E-06
140 0.2838E-06
141 0.2838E-06
142 0.2838E-06
143 0.2838E-06
144 0.2838E-06
145 0.2838E-06
146 0.2838E-06
147 0.2838E-06
148 0.2838E-06
149 0.2838E-06
150 0.2838E-06
151 0.2838E-06
152 0.2838E-06
153 0.2838E-06
154 0.2838E-06
155 0.2838E-06
156 0.2838E-06
157 0.2838E-06
158 0.2838E-06
159 0.2838E-06
160 0.2838E-06
161 0.2838E-06
162 0.2838E-06
163 0.2838E-06
164 0.2838E-06
165 0.2838E-06
166 0.2838E-06
167 0.2838E-06
168 0.2838E-06
169 0.2838E-06
170 0.2838E-06
171 0.2838E-06
172 0.2838E-06
173 0.2838E-06
174 0.2838E-06
175 0.2838E-06
176 0.2838E-06
177 0.2838E-06
178 0.2838E-06
179 0.2838E-06
180 0.2838E-06
181 0.2838E-06
182 0.2838E-06
183 0.2838E-06
184 0.2838E-06
185 0.2838E-06
186 0.2838E-06
187 0.2838E-06
188 0.2838E-06
189 0.2838E-06
190 0.2838E-06
191 0.2838E-06
192 0.2838E-06
193 0.2838E-06
194 0.2838E-06
195 0.2838E-06
196 0.2838E-06
197 0.2838E-06
198 0.2838E-06
199 0.2838E-06
200 0.2838E-06
201 0.2838E-06
202 0.2838E-06
203 0.2838E-06
204 0.2838E-06
205 0.2838E-06
206 0.2838E-06
207 0.2838E-06
208 0.2838E-06
209 0.2838E-06
210 0.2838E-06
211 0.2838E-06
212 0.2838E-06
213 0.2838E-06
214 0.2838E-06
215 0.2838E-06
216 0.2838E-06
217 0.2838E-06
218 0.2838E-06
219 0.2838E-06
220 0.2838E-06
221 0.2838E-06
222 0.2838E-06
223 0.2838E-06
224 0.2838E-06
225 0.2838E-06
226 0.2838E-06
227 0.2838E-06
228 0.2838E-06
229 0.2838E-06
230 0.2838E-06
231 0.2838E-06
232 0.2838E-06
233 0.2838E-06
234 0.2838E-06
235 0.2838E-06
236 0.2838E-06
237 0.2838E-06
238 0.2838E-06
239 0.2838E-06
240 0.2838E-06
241 0.2838E-06
242 0.2838E-06
243 0.2838E-06
244 0.2838E-06
245 0.2838E-06
246 0.2838E-06
247 0.2838E-06
248 0.2838E-06
249 0.2838E-06
250 0.2838E-06
251 0.2838E-06
252 0.2838E-06
253 0.2838E-06
254 0.2838E-06
255 0.2838E-06
256 0.2838E-06
257 0.2838E-06
258 0.2838E-06
259 0.2838E-06
260 0.2838E-06
261 0.2838E-06
262 0.2838E-06
263 0.2838E-06
264 0.2838E-06
265 0.2838E-06
266 0.2838E-06
267 0.2838E-06
268 0.2838E-06
269 0.2838E-06
270 0.2953E-38
ERROR:: IterSolve: Failed convergence tolerances.
i.) Your linear system convergence tolerance setting is 1.0e-8.
ii.)The solver failed to converge in the 270th iteration, when the tolerance jumped from 1.0e-6 (within tolerance) to 1.0e-38 (far smaller tolerance width than the set 1.0e-8).
I express herein my rough guesses:
1. Try changing Linear System Preconditioning tools from ILU1 to others.
2. What is the fineness of your axisymmetric meshes?
For more information, you can view the following posts:
viewtopic.php?f=3&t=3920&p=13729&hilit= ... 5be#p13729
viewtopic.php?f=3&t=3372&p=13061&hilit= ... 5be#p13061
Yours Sincerely
Anil Kunwar
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Re: Navier-Stokes Solver
Hi Hamed,
1. I changed the keyword "Pressure" in BCs to the keyword "External Pressure" in your solver input file and the solver converged.
Results
Yours Sincerely
Anil Kunwar
1. I changed the keyword "Pressure" in BCs to the keyword "External Pressure" in your solver input file and the solver converged.
Code: Select all
!Inlet
Boundary Condition 1
...
External Pressure = -1.01e5
...
Code: Select all
!Outlet
Boundary Condition 2
...
External Pressure = -1.0e5
...
Anil Kunwar
Last edited by annier on 28 Jun 2015, 17:42, edited 4 times in total.
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Re: Navier-Stokes Solver
Hi Hamed,
2. I applied Pressure (force) boundary conditions in BCs as:
And, then it converged.
The results are as following:
Please Note that:
Anil Kunwar
2. I applied Pressure (force) boundary conditions in BCs as:
Code: Select all
! inlet
Boundary Condition 1
Target Boundaries = 1
...
Pressure 1 = 30.0
Pressure 2 = 40.0
...
End
Code: Select all
! outlet
Boundary Condition 2
Target Boundaries = 3
...
Pressure 1 = 0
Pressure 2 = 0
...
End
The results are as following:
Please Note that:
Yours SincerelyElmer_Models_Manual wrote:Boundary Condition bc id
...
External Pressure Real
An external pressure boundary condition directed normal to the surface.
...
Pressure i Real
A pressure force in the given direction i= 1,2,3 (It has a unit of Newtons/m^2. In Elmer, Force at boundary condition has the unit of N/m^2)
...
Anil Kunwar
Last edited by annier on 28 Jun 2015, 17:38, edited 1 time in total.
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice