This pressure boundary condition maintains a (subsonic) Mach number at an outlet patch by dynamically adjusting the static outlet pressure. It makes it possible, for example, to simulate the flow in a pre-turbine engine exhaust manifold without resolving details of the flow inside the turbine.
The formulation is derived from a simple model of the gas flow through a nozzle with fixed geometry. The nozzle flow is assumed to be quasi-steady, 1D, isentropic and compressible.
The accompanying boundary conditions for velocity should be pressureInletOutletVelocity
- Source code
This condition can be used in combination with a cyclic pressure jump condition to simulate a fan. The existing fan pressure jump condition implements the fan-normal momentum gain. This new velocity jump condition adds a swirl component.
The velocity jump can be specified in two ways:
- constant velocity
- constant swirl
In the first mode the velocity is calculated as follows:
Where represents the current pressure drop across the cyclic, is the effective radius, is the fan efficiency coefficient and the speed of the fan (in revolutions-per-minute).
In the second mode the inner () and outer () radii are provided instead of , where for and the velocity is given as:
where is the distance from a patch face to the fan axis. Outside and , . The input for this mode is:
origin (0.0453 0.06 0);
If the is not provided the centroid of the patch is taken.
A new irregular wave model based on the frequency-direction spectrum has been added to the suite of available wave models.
The wave height is set according to the equation:
- Source code
- These boundary conditions were supplied by the Environmental Hydraulics Institute IHCantabria
- The code has been updated by OpenCFD and added to the $FOAM_SRC/waveModels library available to the interFoam family of solvers