Dec 10, 2020

Parametric simulations with Ansys

Summary

With the arrival of the latest Ansys update; 2020 R2, a new licensing model is introduced for parametric simulations. The model introduces the ability for running multiple simulations with a single solver license utilizing HPC licenses.

Background

As many of you may know, Ansys Workbench enabling you to control almost every part of your simulation workflow through the use of programmable parameters. For example, parameters can be introduced to vary mass flow, loads, material properties, mesh controls, friction factors, or even geometrical variations, etc. Inside Ansys Workbench, the parameters are controlled from the parameter set, see Fig. 1.

Figure 1, Workbench simulation task with parameters.

What do we gain from running a parametric sweep of some significant parameter? We gain knowledge!

Knowledge and insight about how our product responds to changing conditions or tolerance variations. From these variations, the corresponding simulation response will give us insight into which parameters are more prone to change the performance than others. On the basis of these results, it is also easy to make a response curve or surface to represent the impact on e.g. pressure drop, using e.g. optiSLang as seen in Fig. 2.

Figure 2, Response surface of pressure drop with three parameters.

How it works

The new licensing model for parametric simulations uses the HPC licenses to multiply the solver license. This expand the usefulness of HPC licenses from speed-up simulations (most Ansys software scales linearly, i.e. time to results will halve with twice as many compute-cores) to perform parameter sweeps through running multiple simulations in parallel. Combining the two treats and adding in high-performance computing, either on-premises or in the cloud, you will have multiple results in less time than today, making the decisions more intelligent – based on accurate and multiple results.

For example, consider an Ansys FEA simulation where we would like to perform four different solutions using 4 cores each. For each set of solver running simultaneously, we would require 8 HPC licenses. Resulting in a total of 32 HPC licenses in order to start four solver processes at the same time. If the wall clock time per solver process is very long we can in addition introduce HPC licenses to increase the core count per solver process. For example, the above example would require 48 HPC licenses to run 4 solver processes simultaneously on 8 cores per solver process, see Table 1.