TUFLOW General Discussion: Difference between revisions

Where k is the viscosity coefficient in Pa.s when ''n'' = 1. Where ''n''=1, this relates to a Newtonian fluid. You can then use an appropriate value for tau0, the stress required to make the fluid move. The Non-Newtonian model uses the Herschel-Bulkley approach which can be used to model Newtonian fluids with different viscosities. See section 5.4 of the <u>[https://downloads.tuflow.com/TUFLOW/Releases/2020-10/TUFLOW%20Release%20Notes.2020-10-AD.pdf 2020 Release Notes]</u> for more information.

It should be seen that where Ƭ0''Ƭ₀=''0, the Herschel-Bulkley equation is the same as the power law model. If ''n'' is 1, then the Herschel-Bulkley equation is the same as the Bingham Plastic model. If Ƭ0''Ƭ₀''=0 and ''n'' =1, then the Herschel-Bulkley equation is the same as the Newtonian fluid approach. By using the Herschel-Bulkley equation as a Newtonian model, it does allow you to define the viscosity coefficient for the fluid. InThere yourmay casebe you’lla need to convert the viscosity from centiStokes to Pa S (if using an N''n'' value of 1). YouIt canis thenalso possible to define the fluid density using the <font color="blue"><tt>Density of Water</tt></font> command you mention.

This uses a ''n'' value of 1, a Ƭ0''Ƭ₀''=0 and a viscosity coefficient of 0.001 Pa S which is a typical viscosity of water at 20 ℃. This should give comparable outputs to a standard TUFLOW model without the Non-Newtonian functionality.