I am experiencing failure of N-S convergence, so I am giving a shot if you could look at my solver parameters. In the case these solvers are involved : Mesh Update solver - Heat eq. solver (direct linear system solver used) - NS solver - Phase change solver. Courant number is low enough so it's not the problem of timestep size. Mesh seems to be good as well and no temperature oscillations occur, so I guess it's parameters of N-S that doesn't let computing to be finished properly.
N-S solver:
Code: Select all
Solver 3
Equation = "Navier-Stokes"
Nonlinear System Max Iterations = 1
Nonlinear System Convergence Tolerance = 1.0e-6
Nonlinear System Newton After Iterations = 3
Nonlinear System Newton After Tolerance = 1.0e-3
Nonlinear System Relaxation Factor = 1
Linear System Solver = "Iterative"
Linear System Iterative Method = "BiCGStab"
Linear System Convergence Tolerance = 1.0e-9
Linear System Max Iterations = 100
Linear System Preconditioning = ILU5
Steady State Convergence Tolerance = 1.0e-05
Stabilize = Logical True
End
two examples of different convergence failures:
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FlowSolve:
FlowSolve:
FlowSolve: -------------------------------------
FlowSolve: NAVIER-STOKES ITERATION 1
FlowSolve: -------------------------------------
FlowSolve:
FlowSolve: Starting Assembly...
FlowSolve: Assembly:
FlowSolve: Assembly done
DefUtils::DefaultDirichletBCs: Setting Dirichlet boundary conditions
DefUtils::DefaultDirichletBCs: Dirichlet boundary conditions set
FlowSolve: Dirichlet conditions done
CRS_IncompleteLU: ILU(5) (Real), Starting Factorization:
CRS_IncompleteLU: ILU(5) (Real), NOF nonzeros: 7114771
CRS_IncompleteLU: ILU(5) (Real), filling (%) : 645
CRS_IncompleteLU: ILU(5) (Real), Factorization ready at (s): 1.46
1 0.5494E-01
2 0.9326E+04
3 0.5339E-01
4 0.3500E-01
5 0.2921E-01
6 0.3466E-03
7 0.2232E-03
8 0.1834E-04
9 0.3988E-06
10 0.2089E-06
11 0.1250E-08
12 0.1134E-08
13 0.1135E-08
14 0.1134E-08
15 0.1134E-08
16 0.1134E-08
17 0.1134E-08
18 0.1134E-08
19 0.1134E-08
20 0.1135E-08
21 0.1134E-08
22 0.1135E-08
23 0.1135E-08
24 0.1135E-08
25 0.1135E-08
26 0.1135E-08
27 0.6833E-08
28 0.6493E-08
29 0.6750E-08
30 0.6984E-08
31 0.7249E-08
32 0.8652E-08
33 0.1025E-06
34 0.4479E-05
35 0.3944E-05
36 0.2842E-04
37 0.2621E-04
38 0.4182E-04
39 0.6126E-04
40 0.5970E-04
41 0.1226E-03
42 0.1176E-03
43 0.1593E-03
44 0.1928E-03
45 0.1903E-03
46 0.1924E-03
47 0.2081E-03
48 0.2119E-03
49 0.1519E-02
50 0.9047E-02
51 0.8382E-02
52 0.2259E-01
53 0.2376E-01
54 0.2429E-01
55 0.2322E-01
56 0.2363E-01
57 0.2389E-01
58 0.2403E-01
59 0.2426E-01
60 0.2459E-01
61 0.5599E-01
62 0.5559E-01
63 0.9264E-01
64 0.9135E-01
65 0.8715E-01
66 0.8690E-01
67 0.9160E+00
68 0.8176E+00
69 0.7951E+00
70 0.9382E+00
71 0.9371E+00
72 0.1113E+01
73 0.1070E+01
74 0.1025E+01
75 0.1027E+01
76 0.1043E+01
77 0.1046E+01
78 0.1058E+01
79 0.1061E+01
80 0.1078E+01
81 0.1060E+01
82 0.1063E+01
83 0.1065E+01
84 0.1069E+01
85 0.1066E+01
86 0.1064E+01
87 0.1065E+01
88 0.1274E+01
89 0.1287E+01
90 0.1340E+01
91 0.1351E+01
92 0.1368E+01
93 0.1399E+01
94 0.1421E+01
95 0.1474E+01
96 0.1483E+01
97 0.1492E+01
98 0.1495E+01
99 0.1515E+01
100 0.1780E+01
101 0.1780E+01
ERROR:: IterSolve: Failed convergence tolerances.
Code: Select all
FlowSolve:
FlowSolve:
FlowSolve: -------------------------------------
FlowSolve: NAVIER-STOKES ITERATION 1
FlowSolve: -------------------------------------
FlowSolve:
FlowSolve: Starting Assembly...
FlowSolve: Assembly:
FlowSolve: Assembly done
DefUtils::DefaultDirichletBCs: Setting Dirichlet boundary conditions
DefUtils::DefaultDirichletBCs: Dirichlet boundary conditions set
FlowSolve: Dirichlet conditions done
CRS_IncompleteLU: ILU(2) (Real), Starting Factorization:
CRS_IncompleteLU: ILU(2) (Real), NOF nonzeros: 2263861
CRS_IncompleteLU: ILU(2) (Real), filling (%) : 205
CRS_IncompleteLU: ILU(2) (Real), Factorization ready at (s): 0.19
1 0.3075E-02
2 0.1020E-03
3 0.6413E-04
4 0.7929E-04
5 0.8642E-04
6 0.5232E-04
7 0.4112E-04
8 0.3913E-04
9 0.3696E-04
10 0.3899E-04
11 0.3668E-04
12 0.3492E-04
13 0.2460E-04
14 0.2424E-04
15 0.2694E-04
16 0.1584E-03
17 0.6350E-04
18 0.2064E-03
19 0.1636E-03
20 0.1056E-03
21 0.1115E-03
22 0.3383E-04
23 0.1958E-04
24 0.2079E-04
25 0.1364E-04
26 0.8091E-05
27 0.4155E-05
28 0.4532E-05
29 0.4395E-05
30 0.8347E-05
31 0.7575E-05
32 0.1198E-04
33 0.3090E-05
34 0.3178E-05
35 0.3104E-05
36 0.9237E-05
37 0.4645E-05
38 0.1465E-04
39 0.4582E-05
40 0.1834E-05
41 0.1757E-05
42 0.2335E-05
43 0.2434E-05
44 0.1417E-04
45 0.2101E-05
46 0.7533E-06
47 0.6956E-06
48 0.7456E-06
49 0.8818E-06
50 0.1662E-05
51 0.7339E-06
52 0.7317E-06
53 0.7370E-06
54 0.6627E-06
55 0.3889E-05
56 0.5810E-06
57 0.4657E-06
58 0.4218E-06
59 0.4156E-06
60 0.4107E-06
61 0.4099E-06
62 0.3975E-06
63 0.4170E-06
64 0.7132E-06
65 0.7391E-06
66 0.7245E-06
67 0.7054E-06
68 0.6373E-06
69 0.6131E-06
70 0.5303E-05
71 0.6147E-06
72 0.7574E-06
73 0.5684E-06
74 0.8169E-06
75 0.5781E-06
76 0.6245E-06
77 0.5963E-06
78 0.5930E-06
79 0.5512E-06
80 0.5521E-06
81 0.5568E-06
82 0.5545E-06
83 0.5619E-06
84 0.5445E-06
85 0.5484E-06
86 0.5646E-06
87 0.5637E-06
88 0.5540E-06
89 0.5523E-06
90 0.9500E-06
91 0.1209E-05
92 0.1047E-05
93 0.1957E-05
94 0.1155E-05
95 0.1136E-05
96 0.9866E-06
97 0.9877E-06
98 0.3991E-06
99 0.2740E-06
100 0.2714E-06
101 0.2714E-06
ERROR:: IterSolve: Failed convergence tolerances.