Some of the mixture dynamic viscosity methods compute the viscosity of the mixture relative to the water viscosity, which is a function of temperature. The mud and debris equations will vary both the water and mixture viscosity with temperatures if these methods are selected and if the user defines a temperature time series. By default, HEC-RAS assumes a temperature of 50o F (10o C). To define a temperature time series, select the Options menu in the Unsteady Flow editor. Select Water Temperature (just above the Non-Newtonian option). Mud and debris flows are usually rapid events, so seasonal temperature changes (like the one in the do not tend to affect the simulations). However, users can define a new, non-default, constant temperature time series editor or use more detailed mixture temperature data if available.
