River energy line slopes uphill at major flow accelerations

RegMeasures / HapuaModel

Physically based model of hāpua morphodynamics

GNU General Public License v3.0

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River energy line slopes uphill at major flow accelerations #3

Open RegMeasures opened 5 years ago

RegMeasures commented 5 years ago

Weird bug - not sure what is going on. Appears to be linked to high froude numbers (~1): IncorrectEnergySlope

RegMeasures commented 5 years ago

Need to check my implementation of the St-Venant equations. An alternative reference to check against which actually explains itself quite well is the Flood Modeller Pro manual: http://help.floodmodeller.com/floodmodeller/#t=Technical_Reference%2F1D_Modelling_Theory%2FTheoretical_Basis%2FHydrodynamic_Channel_Flows.htm http://help.floodmodeller.com/floodmodeller/#t=Technical_Reference%2F1D_Modelling_Theory%2FDiscretisation.htm

RegMeasures commented 5 years ago

Can't find any errors - I think this might relate to issues at froude numbers getting close to 1 - #2

RegMeasures commented 5 years ago

This causes issues with bedload transport as it relies on energy slope - which goes negative!

RegMeasures commented 5 years ago

Some of this is related to discretisation - plotting reach energy rather than node energy reduces the issue but doesn't resolve it completely - possibly need to reduce cross-section spacing in high energy loss reaches?

RegMeasures commented 4 years ago

Maybe this is happening because I am relaxing the convective acceleration term (i.e. beta=0)? I think this could be the reason but need to do some testing...