Adaptive Timestepping problems
 

Hello everyone,



I am experiencing problems with adaptive timestepping.

My settings are as follows:



Maximum Timestep = 0.0005 [s]
Minimum Timestep = 0.0001 [s]
Option = Number of Coefficient Loops
Target Maximum Coefficient Loops = 15
Target Minimum Coefficient Loops = 8
Timestep Decrease Factor = 0.8
Timestep Increase Factor = 1.06

with



CONVERGENCE CONTROL:
Maximum Number of Coefficient Loops = 20
Minimum Number of Coefficient Loops = 5
Timescale Control = Coefficient Loops

CONVERGENCE CRITERIA:
Residual Target = 0.00001
Residual Type = RMS


I am simulating filling of a bottle using inhomogeneous MUSIG model. Adaptive timestepping was working fine for one fluid. As I changed the fluid, the simulation converged after 5-6 loops, but does not stop the iteration and adapt the timestep. It still calculates all 20 loops, while reaching RMS of 1E-09 and lower and stays at the lowest timestep.



Thanks in advance!

Hello everyone,


Short Update:


I at least found that my Size Fractions from the MUSIG model were not converging completely. What I still not understand, when RMS for Size Fractions are below 1e-4 the iteration loop stops and timestep adaption is working, however I put the Residual Target at 1e-5.



How is this possible?