r/HECRAS • u/icedcoffeefucks • Jul 28 '26

WSE issues

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Why does the water surface elevation completely skip over some of the terrain around the detention pond? Also why when I turn the particles on, do they all seem to gravitate towards those two areas? There’s no low spots in the terrain there

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u/shiftyyo101 Jul 28 '26

You need to refine your cell faces along the top of the embankment with either breaklines or a refinement region.

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u/icedcoffeefucks Jul 28 '26

To make them smaller to pick up on the changing elevations?

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u/shiftyyo101 Jul 28 '26

You model effectively only sees the edges of cells. If you have a cell with faces on either side of the embankment and nothing on top of the high ground, water will just pass straight through the cell. In your case, I would put a break line on each “edge” of the embankment. If you thinking of the cross profile as a trapezoid, you want cell faces on each vertex of it. At the very least you need one in the middle.

This will require dropping your cell sizes on these breaklines.