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63 lines
2.0 KiB
HTML
63 lines
2.0 KiB
HTML
<HTML>
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<CENTER><A HREF = "http://www.cfdem.com">CFDEMproject WWW Site</A> - <A HREF = "CFDEMcoupling_Manual.html#comm">CFDEM Commands</A>
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<HR>
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<H3>voidfractionModel_bigParticleVoidFraction command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<P>Defined in couplingProperties dictionary.
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<PRE>voidfractionModel bigParticle;
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bigParticleProps
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{
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maxCellsPerParticle number1;
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alphaMin number2;
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scaleUpVol number3;
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weight number4;
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}
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</PRE>
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<UL><LI><I>number1</I> = max number of cells covered by a partilce (search will fail when more than <I>number1</I> cells are covered by the particle)
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<LI><I>number2</I> = mininmum limit for voidfraction
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<LI><I>number3</I> = diameter of the particle's representation is artificially increased according to <I>number3</I> * Vparticle, volume remains unaltered!
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<LI><I>number4</I> = scaling of the particle volume to account for porosity or agglomerations.
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>voidfractionModel bigParticle;
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bigParticleProps
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{
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maxCellsPerParticle 1000;
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alphaMin 0.10;
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scaleUpVol 5.0;
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weight 1.;
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}
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</PRE>
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<P><B>Description:</B>
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<P>The bigParticle voidFraction model is supposed to be used when a particle (or it's representation) is bigger than a CFD cell. The voidfraction field is set in those cell whose centres are inside the particle which results in a stairstep representation of the bodies within the mesh (i.e. voidfraction is either 1 (fluid) of zero (solid)). For archiving accurate results, approx. 8 cells per particle diameter are necessary.
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</P>
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<P>The region of influence of a particle can be increased artificially by "scaleUpVol", which blows up the particles, but keeps their volume (for voidfraction calculation) constant.
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</P>
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<P>The particle volume occupied in the CFD domain can be adjusted by the parameter "weight", using Vparticle=dsphere^3*pi/6*weight.
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</P>
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<P>Parts of this sub-model contributed by Alice Hager, JKU.
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</P>
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<P><B>Restrictions:</B> none.
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "voidfractionModel.html">voidfractionModel</A>
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</P>
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</HTML>
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