Dear Sir,
We have some test results as stated below after so many attempts on reducing runtime of plasma module for simulating a chamber with CCP type.
a. We tested several cases (such as argon_gec_icp and our own cases) with different number of cores. However, the parallel performance is not as good as expect, which is less than 40 % or even lower in some cases.
b. We tested the cases with both direct and iterative solvers with different preconditioners. The difference is around 30% in the cases we tested.
c. For a plasma simulation with many species (>20), we tried to solve the solution segregatedly (with several different combination), reducing the runtime dramatically (more than 10 times speedup in some cases). But it seems not good enough to resolve the difficulty to run the simulation within the “acceptable” runtime. Because of the physical constraint, we can only run the simulation with max. time step size as 10^(-10) (s) though COMSOL makes use of the fully coupled scheme which is numerically stable for larger time step size. Furthermore, it requires several thousand of RF cycles for the simulation to reach the quasi-steady solution. In other words, it may take several days up to weeks to run a simulation, which is not acceptable and practical.
The enclosure is an example of helium discharge with 25 species and 101 reactions. The element number is 110 x 50 which is not a big problem if compared with chamber simulation. If we fix the size of time step to 7x10^(-10), and run the simulation for one cycle (study 2, from 100th to 101st ). It takes about 3000 ~ 4000 (s) with fully coupled scheme, and about 400 (s) with segregated scheme. As stated previously, it will still take “weeks” to run the simulation.
We wonder whether we did anything wrong (We hope we really did). Is there any alternative (solver, segregated scheme, preconditioner, etc.) we can do to tune the example case to reach its optimized conditions? The target is to reduce the runtime to 30 second around for one cycle. Is it possible? Thanks.
KM
We have some test results as stated below after so many attempts on reducing runtime of plasma module for simulating a chamber with CCP type.
a. We tested several cases (such as argon_gec_icp and our own cases) with different number of cores. However, the parallel performance is not as good as expect, which is less than 40 % or even lower in some cases.
b. We tested the cases with both direct and iterative solvers with different preconditioners. The difference is around 30% in the cases we tested.
c. For a plasma simulation with many species (>20), we tried to solve the solution segregatedly (with several different combination), reducing the runtime dramatically (more than 10 times speedup in some cases). But it seems not good enough to resolve the difficulty to run the simulation within the “acceptable” runtime. Because of the physical constraint, we can only run the simulation with max. time step size as 10^(-10) (s) though COMSOL makes use of the fully coupled scheme which is numerically stable for larger time step size. Furthermore, it requires several thousand of RF cycles for the simulation to reach the quasi-steady solution. In other words, it may take several days up to weeks to run a simulation, which is not acceptable and practical.
The enclosure is an example of helium discharge with 25 species and 101 reactions. The element number is 110 x 50 which is not a big problem if compared with chamber simulation. If we fix the size of time step to 7x10^(-10), and run the simulation for one cycle (study 2, from 100th to 101st ). It takes about 3000 ~ 4000 (s) with fully coupled scheme, and about 400 (s) with segregated scheme. As stated previously, it will still take “weeks” to run the simulation.
We wonder whether we did anything wrong (We hope we really did). Is there any alternative (solver, segregated scheme, preconditioner, etc.) we can do to tune the example case to reach its optimized conditions? The target is to reduce the runtime to 30 second around for one cycle. Is it possible? Thanks.
KM