Location
Virtual
Start Date
7-5-2021 12:00 AM
End Date
7-8-2021 12:00 AM
Description
Downstream migration over weir structures has been a mostly neglected element of ecological continuity in the last decades. The guidelines currently applied in Germany to prevent damage to fish do not sufficiently consider the conditions present at weirs. To improve knowledge of the risks of fish passage over a weir due to physical strike, pressure changes and shear stress, a numerical method using the three-dimensional computational fluid dynamics package OpenFOAM® was developed to simulate fish passage over a weir by tracking passively transported particles. In this study, the method is tested on an overshot and an undershot weir and the results are compared to known critical parameters to assess the hazard potential of these weirs. As expected, pressure changes are much more relevant in the undershot scenario, physical strike and shear stress are dominant in the overshot scenario. Altogether both situations result in only collisions with low impact velocities and relatively low shear stress and pressure changes, assuming little threat to fish due to the relatively low drop height and absence of baffle blocks or an end sill. To improve the methods reliability, additional enhancements are necessary.
Included in
Numerical Simulation of Fish Passage Over a Weir
Virtual
Downstream migration over weir structures has been a mostly neglected element of ecological continuity in the last decades. The guidelines currently applied in Germany to prevent damage to fish do not sufficiently consider the conditions present at weirs. To improve knowledge of the risks of fish passage over a weir due to physical strike, pressure changes and shear stress, a numerical method using the three-dimensional computational fluid dynamics package OpenFOAM® was developed to simulate fish passage over a weir by tracking passively transported particles. In this study, the method is tested on an overshot and an undershot weir and the results are compared to known critical parameters to assess the hazard potential of these weirs. As expected, pressure changes are much more relevant in the undershot scenario, physical strike and shear stress are dominant in the overshot scenario. Altogether both situations result in only collisions with low impact velocities and relatively low shear stress and pressure changes, assuming little threat to fish due to the relatively low drop height and absence of baffle blocks or an end sill. To improve the methods reliability, additional enhancements are necessary.