KR211: How to calculate angular momentum or swirl/tumble for engine cases run in Fluent using CFD-Post?

First, the user needs to set up the following environment variable to ask Post to use cell value for integration. If expression is involved in volume integral, node value will be used.

The user will then need to define expressions. But the expressions have been done. One only needs to copy/paste the following, and save it into .cst file, a state file. Once the file is loaded into CFD-post. All expressions will be available for usage.

Note that the expression assumes that the integration is over a zone called fluid. You might need to change that in every expression and save it before loading it into post.

# will need to change the fluid zone names
IC Post OmegaEngine = 2 * pi * 1200. [min^-1]
IC Post Mass = volumeInt(Density)@Fluid
IC Post xmid = volumeInt(Density*x)@Fluid / IC Post Mass
IC Post ymid = volumeInt(Density*y)@Fluid / IC Post Mass
IC Post zmid = volumeInt(Density*z)@Fluid / IC Post Mass
IC Post AngularMomX = volumeInt(Density * ((y-IC Post ymid)*Velocity w-(z-IC Post zmid)*Velocity v))@Fluid
IC Post AngularMomY = volumeInt(Density * ((z-IC Post zmid)*Velocity u-(x-IC Post xmid)*Velocity w))@Fluid
IC Post AngularMomZ = volumeInt(Density * ((x-IC Post xmid)*Velocity v-(y-IC Post ymid)*Velocity u))@Fluid
IC Post IntertiaX = volumeInt(Density*((y-IC Post ymid)^2+(z-IC Post zmid)^2))@Fluid
IC Post IntertiaY = volumeInt(Density*((z-IC Post zmid)^2+(x-IC Post xmid)^2))@Fluid
IC Post IntertiaZ = volumeInt(Density*((x-IC Post xmid)^2+(y-IC Post ymid)^2))@Fluid
IC Post AngularMom = sqrt(IC Post AngularMomX^2+IC Post AngularMomY^2+IC Post AngularMomZ^2)
angular = volumeInt(Density*Velocity Circumferential*Radial Angular Coordinate)@Fluid
IC Post SwirlXRatio = IC Post AngularMomX / IC Post IntertiaX / IC Post OmegaEngine
IC Post SwirlYRatio = IC Post AngularMomY / IC Post IntertiaY / IC Post OmegaEngine
IC Post SwirlZRatio = IC Post AngularMomZ / IC Post IntertiaZ / IC Post OmegaEngine


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