HPC FAQ: Difference between revisions

For deep, fast flowing waterways, 1st order HPC tends to produce higher water levels and steeper gradients compared with the Classic and HPC 2nd order solutions. These differences can exceed 10% of the primary flow path depth. Typically, lower Manning’s n values are required for HPC 1st order (or the original TUFLOW GPU), to achieve a similar result to TUFLOW Classic or HPC 2nd order.

Significant differences may occur at 2D HQ boundaries. Classic treats the 2D HQ boundary as one HQ boundary across the whole HQ line, setting a water level based on the total flow across the line. Due to model splitting to parallelise the 2D domain across CPU or GPU cores, HPC applies the HQ boundary slope to each individual cell along the boundary. As with all HQ boundaries, the effect of the boundary should be well away from the area of interest, and sensitivity testing carried out to demonstrate this.

Yes, if transitioning from Classic to HPC (or any other solver), it is best practice to compare the results, and if there are unacceptable differences, or the model calibration has deteriorated, to fine-tune the model performance through adjustment of key parameters.

Typically, between TUFLOW Classic and HPC 2nd order this would only require a slight adjustment to Manning’s n values, any additional form losses at bends/obstructions or eddy viscosity values. Regardless, industry standard Manning’s n and other key parameters should only be used/needed. Use of non-standard values is a strong indicator there are other issues such as inflows, poor boundary representation or missing/erroneous topography.

Solution Scheme == HPC

Hardware == GPU

=Why does my TUFLOW HPC simulation take longer than TUFLOW Classic?=

The primary reasons why the HPC may run slow are discussed below: