<h3>Results for a 2d circular shell testcase</h3>
-If we run the program as shown above, the output will look roughly like this,
-producing the final part of the output after some 2 days when run on 10
-processors:
+If we run the program as shown above (with the parameter file in the
+directory), the output will look roughly
+like this when run on 50 processors:
<code>
<pre>
-Number of active cells: 12288 (on 6 levels)
-Number of degrees of freedom: 162432 (99840+12672+49920)
+Number of active cells: 12,288 (on 6 levels)
+Number of degrees of freedom: 186,624 (99,840+36,864+49,920)
Timestep 0: t=0 years
- Assembling...
+
Rebuilding Stokes preconditioner...
- Solving...
- 14 BiCGStab iterations for Stokes subsystem.
- Maximal velocity: 1.80187 cm/year
- Time step: 607937 years
- 15 CG iterations for temperature
- Temperature range: 973 4273.27
+ Solving Stokes system... 41 iterations.
+ Maximal velocity: 60.672 cm/year
+ Time step: 17661 years
+ 17 CG iterations for temperature
+ Temperature range: 973 4273.16
-Number of active cells: 17988 (on 7 levels)
-Number of degrees of freedom: 240504 (147888+18672+73944)
+Number of active cells: 16,803 (on 7 levels)
+Number of degrees of freedom: 266,589 (144,120+50,409+72,060)
Timestep 0: t=0 years
- Assembling...
+
Rebuilding Stokes preconditioner...
- Solving...
- 3 BiCGStab iterations for Stokes subsystem.
- Maximal velocity: 1.52763 cm/year
- Time step: 357565 years
- 17 CG iterations for temperature
- Temperature range: 973 4274.08
+ Solving Stokes system... 33 iterations.
+ Maximal velocity: 60.6718 cm/year
+ Time step: 11032.2 years
+ 19 CG iterations for temperature
+ Temperature range: 973 4273.16
-Number of active cells: 34716 (on 8 levels)
-Number of degrees of freedom: 474550 (291896+36706+145948)
+Number of active cells: 21,024 (on 8 levels)
+Number of degrees of freedom: 339,999 (184,618+63,072+92,309)
Timestep 0: t=0 years
- Assembling...
+
Rebuilding Stokes preconditioner...
- Solving...
- 3 BiCGStab iterations for Stokes subsystem.
- Maximal velocity: 2.97931 cm/year
- Time step: 91574.3 years
- 17 CG iterations for temperature
- Temperature range: 973 4277.31
-
-Timestep 1: t=91574.3 years
- Assembling...
- Solving...
- 2 BiCGStab iterations for Stokes subsystem.
- Maximal velocity: 2.86431 cm/year
- Time step: 95251.1 years
+ Solving Stokes system... 33 iterations.
+ Maximal velocity: 60.6835 cm/year
+ Time step: 5520.09 years
18 CG iterations for temperature
- Temperature range: 973 4277.31
+ Temperature range: 973 4273.44
+
+Timestep 1: t=5520.09 years
+
+ Solving Stokes system... 34 iterations.
+ Maximal velocity: 61.9054 cm/year
+ Time step: 5410.41 years
+ 18 CG iterations for temperature
+ Temperature range: 973 4273.44
+
+Timestep 2: t=10930.5 years
+
+ Solving Stokes system... 24 iterations.
+ Maximal velocity: 63.1348 cm/year
+ Time step: 5304.37 years
+ 18 CG iterations for temperature
+ Temperature range: 973 4273.44
[...]
-Timestep 53906: t=9.99985e+08 years
- Assembling...
- Solving...
- 4 BiCGStab iterations for Stokes subsystem.
- Maximal velocity: 12.2898 cm/year
- Time step: 22199.6 years
+Timestep 100: t=283833 years
+
+ Solving Stokes system... 23 iterations.
+ Maximal velocity: 168.248 cm/year
+ Time step: 1732.43 years
18 CG iterations for temperature
- Temperature range: 973 4273.07
+ Temperature range: 973 4285.06
+
+Number of active cells: 42,681 (on 8 levels)
+Number of degrees of freedom: 694,359 (377,544+128,043+188,772)
+
+---------------------------------------------+------------+------------+
-| Total wallclock time elapsed since start | 1.87e+05s | |
+| Total wallclock time elapsed since start | 140s | |
| | | |
| Section | no. calls | wall time | % of total |
+---------------------------------+-----------+------------+------------+
-| Assemble Stokes system | 53909 | 1.06e+04s | 5.7% |
-| Assemble temperature matrices | 5393 | 913s | 0.49% |
-| Assemble temperature rhs | 53909 | 1.24e+04s | 6.6% |
-| Build Stokes preconditioner | 5393 | 4.52e+03s | 2.4% |
-| Solve Stokes system | 53909 | 6.94e+04s | 37% |
-| Solve temperature system | 53909 | 2.34e+04s | 13% |
-| Postprocessing | 2157 | 5.51e+03s | 2.9% |
-| Refine mesh structure, part 1 | 5392 | 4.71e+04s | 25% |
-| Refine mesh structure, part 2 | 5392 | 1.02e+03s | 0.55% |
-| Setup dof systems | 5393 | 1.11e+04s | 5.9% |
+| Assemble Stokes system | 103 | 7.08s | 5.1% |
+| Assemble temperature matrices | 12 | 0.702s | 0.5% |
+| Assemble temperature rhs | 103 | 10.3s | 7.3% |
+| Build Stokes preconditioner | 12 | 3.6s | 2.6% |
+| Solve Stokes system | 103 | 103s | 74% |
+| Solve temperature system | 103 | 8.13s | 5.8% |
+| Postprocessing | 3 | 0.417s | 0.3% |
+| Refine mesh structure, part 1 | 12 | 0.859s | 0.61% |
+| Refine mesh structure, part 2 | 12 | 1.15s | 0.82% |
+| Setup dof systems | 13 | 4.13s | 2.9% |
+---------------------------------+-----------+------------+------------+
+
+[...]
+
+Timestep 7092: t=1.00027e+08 years
+
+ Solving Stokes system... 26 iterations.
+ Maximal velocity: 8.08888 cm/year
+ Time step: 35734.5 years
+ 18 CG iterations for temperature
+ Temperature range: 973 4273.04
+
+
+
++---------------------------------------------+------------+------------+
+| Total wallclock time elapsed since start | 8.36e+03s | |
+| | | |
+| Section | no. calls | wall time | % of total |
++---------------------------------+-----------+------------+------------+
+| Assemble Stokes system | 7095 | 482s | 5.8% |
+| Assemble temperature matrices | 712 | 40.6s | 0.49% |
+| Assemble temperature rhs | 7095 | 671s | 8% |
+| Build Stokes preconditioner | 712 | 231s | 2.8% |
+| Solve Stokes system | 7095 | 5.99e+03s | 72% |
+| Solve temperature system | 7095 | 578s | 6.9% |
+| Postprocessing | 143 | 19.3s | 0.23% |
+| Refine mesh structure, part 1 | 711 | 48.7s | 0.58% |
+| Refine mesh structure, part 2 | 711 | 68.6s | 0.82% |
+| Setup dof systems | 712 | 223s | 2.7% |
++---------------------------------+-----------+------------+------------+
+
</pre>
</code>
+You can extrapolate from this how long a simulation would take for a
+given number of time steps (the time
+steps ultimately settles on somewhere around 20,000 years, so
+computing for one billion years will take 50,000 time steps, give or take 20%).
As can be seen here, we spend most of the compute time in assembling linear
-systems, refining the mesh, and in particular in solving the Stokes and
-temperature linear systems.
+systems and — above all — in solving Stokes systems.
-We can clearly not show all output files produced by this program, so let us
+We can clearly not show all output files produced by this program when
+run for a longer period of time, so let us
only show the output from every 2500th time step here:
<table>
<tr>