Learning Forum

[Rameez_ul_Haq]

I have a CFX solution connected to a static structural. I want to proceed in this manner: 0.1s, 0.2s, 0.3s, 0.4s, 0.5s, 0.6s, 0.7s, 0.8s, 0.85s, 0.9s, 0.95s, 1s. The total load substeps are 12, but the time period is not even. I am doing this since the analysis is resulting in high element distortion error after 0.8s, therefore after this time substep, I want to apply the load more slowly.

The corresponding scale for pressure is: 0.878, 1.756, 2.634, 3.512, 4.39, 5.268, 6.146, 7.024, 7.463, 7.902, 8.341, 8.78. I inputted these scale factors in the Scale column and inputted the time as already mentioned under the Analysis Time (s) column. Source Time (s) is kept as 0 for all the steps.

I was trying to use these step controls; Number of Steps = 1, Current Step Number = 1, Step End Time = 1, Auto Time Stepping = OFF, Number of Substeps = 12.

I was expecting the analysis to being with time substep = 0.1 sec since I have manually entered it, with a pressure scale factor of 0.878, but unfortunately the time began at 0.0833 sec i.e. 1/12 sec. The analysis actually ignored by manual entering of the time substeps and the corresponding CFX pressure scale factors, and an even time substeps began to be used by the solver. I am confused why is this happening and how can make the analysis work in the manner I want it to.

[Rahul Kumbhar]

You need to set Number of Steps = 12. Thus there will be 12 load steps. Then use 'Current Step Number' to define the 'Step End Time' and 'Number of Substeps' for each load step. For example set Current Step Number = 1 and Step End Time = 0.1, Auto Time Stepping = OFF, Number of Substeps = xxx. and Current Step Number = 2 and Step End Time = 0.2, Auto Time Stepping = OFF, Number of Substeps = yyy...etc.

[Rameez_ul_Haq]

,well, I want to observe the results at 1 sec and I want to have just one substep for each load step, so are these settings correct? I am choosing only 1 substep since I want the analysis to be conducted at only those timesteps which I have entered.
Number of Steps = 12, Current Step Number = 12, Step End Time = 1, Auto Time Stepping = OFF, Number of Substeps = 1.

[Rahul Kumbhar]

yes, the above setting will set substep = 1 for loadstep number 12.

[Rameez_ul_Haq]

,you mean to say that it will put substep = 1 for each loadstep, right? I mean for each of the 12 loadsteps, right? Or just the last loadstep i.e. number 12?

[Rameez_ul_Haq]

,would be glad if you could provide a reply on this :)

[Rameez_ul_Haq]

,maybe you could help please :)

[Rahul Kumbhar]

to set 1 substep for each load step, set Current Step Number = 1,2,3..etc and for each load step set substep number. So you need to do this 12 times from current step number 1 to 12.

[peteroznewman]

I have no experience with FSI problems, sorry.