HPC FAQ: Difference between revisions

* The CME%, which is an excellent indicator that the Classic 2D solver is numerically converging, is not generally of use for HPC, which is volume conserving and effectively 0% subject to numerical precision. Non-zero whole of model CME% for HPC 1D/2D linked models is usually an indication of either the 1D and 2D adaptive timesteps being significantly different, or a poorly configured 1D/2D link.

 

This is largely based on hardware that is used to run HPC models (CPU and GPU) and its performance. On average, HPC using GPU hardware runs about 10 times faster than Classic and about 30 times faster than HPC using CPU with two CPU threads (current default is 4). Even though HPC using CPU hardware is in general slower than Classic, more CPU threads can be used to achieve faster run times. As TUFLOW Classic is not parallelised it can only run on one CPU thread and cannot be further improved even with available CPU resources.<br>

 

The change in runtime can be due to different timestepping applied with the new default - mesh size insensitive turbulence model - Wu instead of Smagorinsky. To confirm this is the case, test run your model with 2020release and the following commands:<br>

<font color="blue"><tt>Viscosity Formulation </tt></font> <font color="red"><tt>==</tt></font><tt> Smagorinsky</tt> <br>