KR211: How to calculate angular momentum or swirl/tumble for engine cases run in Fluent using CFD-Post?
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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. CFDPOST_BOUNDARY_DATA_FROM_ELEMENTS=1 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 LIBRARY: CEL: EXPRESSIONS: 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 END END END |
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