The MachNo
function object computes the Mach number as a volScalarField
.
The Mach number is a dimensionless quantity representing the ratio of flow velocity past a boundary to the local speed of sound:
\[ M = \frac{|\u|}{\sqrt{\gamma p/\rho}} \]
where
\(M \) | = | Mach number |
\(\u \) | = | Velocity |
\(\gamma \) | = | The ratio of specific heat of a gas at a constant pressure to heat at a constant volume |
\(p \) | = | Static pressure |
\(\rho \) | = | Fluid density |
Operand | Type | Location |
---|---|---|
input | volVectorField | $FOAM_CASE/<time>/<inpField> |
output file | - | - |
output field | volScalarField | $FOAM_CASE/<time>/<outField> |
Example of the MachNo
function object by using functions
sub-dictionary in system/controlDict
file:
MachNo1 { // Mandatory entries (unmodifiable) type MachNo; libs (fieldFunctionObjects); // Optional (inherited) entries field <inpField>; result <fieldResult>; region region0; enabled true; log true; timeStart 0; timeEnd 1000; executeControl timeStep; executeInterval 1; writeControl timeStep; writeInterval 1; }
where the entries mean:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type | Type name: MachNo | word | yes | - |
libs | Library name: fieldFunctionObjects | word | yes | - |
The inherited entries are elaborated in:
Example by using the postProcess
utility:
postProcess -func MachNo
Tutorial:
Source code:
History