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Solution Strategies for Inviscid Flows
Since inviscid flow problems will usually involve high-speed flow, you may have to reduce the under-
relaxation factors for momentum (if you are using the pressure-based solver) or reduce the Courant
number (if you are using the density-based solver), in order to get the solution started. Once the flow is
started and the residuals are monotonically decreasing, you can start increasing the under-relaxation
factors or Courant number back up to the default values.

Modifications to the under-relaxation factors and the Courant number can be made in the Solution
Controls task page.

w Solution Controls
The solution strategies for compressible flows apply also to inviscid flows.

(b) Compressible Flows

Compressibility effects are encountered in gas flows at high velocity and/or in which there are large
pressure variations. When the flow velocity approaches or exceeds the speed of sound of the gas or
when the pressure change in the system (∆p/p) is large, the variation of the gas density with pressure
has a significant impact on the flow velocity, pressure, and temperature. Compressible flows create a
unique set of flow physics for which you must be aware of the special input requirements and solution
techniques described in this section. Figures 9.4.1 and 9.4.2 show examples of compressible flows
computed using ANSYS FLUENT.

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