Commit 52f7ae1f authored by andy's avatar andy
Browse files

Merge branch 'master' of /home/noisy3/OpenFOAM/OpenFOAM-dev

parents 0d892704 d46f917b
......@@ -2,7 +2,7 @@
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration |
\\ / A nd | Copyright (C) 2008-2010 OpenCFD Ltd.
\\ / A nd | Copyright (C) 2008-2011 OpenCFD Ltd.
\\/ M anipulation |
-------------------------------------------------------------------------------
License
......@@ -92,12 +92,14 @@ Foam::PairSpringSliderDashpot<CloudType>::PairSpringSliderDashpot
alpha_(readScalar(this->coeffDict().lookup("alpha"))),
b_(readScalar(this->coeffDict().lookup("b"))),
mu_(readScalar(this->coeffDict().lookup("mu"))),
cohesionEnergyDensity_
(
readScalar(this->coeffDict().lookup("cohesionEnergyDensity"))
),
cohesion_(false),
collisionResolutionSteps_
(
readScalar
(
this->coeffDict().lookup("collisionResolutionSteps")
)
readScalar(this->coeffDict().lookup("collisionResolutionSteps"))
),
volumeFactor_(1.0),
useEquivalentSize_(Switch(this->coeffDict().lookup("useEquivalentSize")))
......@@ -116,6 +118,8 @@ Foam::PairSpringSliderDashpot<CloudType>::PairSpringSliderDashpot
scalar G = E/(2.0*(1.0 + nu));
Gstar_ = G/(2.0*(2.0 - nu));
cohesion_ = (mag(cohesionEnergyDensity_) > VSMALL);
}
......@@ -183,13 +187,15 @@ void Foam::PairSpringSliderDashpot<CloudType>::evaluatePair
dBEff *= cbrt(pB.nParticle()*volumeFactor_);
}
scalar normalOverlapMag = 0.5*(dAEff + dBEff) - mag(r_AB);
scalar r_AB_mag = mag(r_AB);
scalar normalOverlapMag = 0.5*(dAEff + dBEff) - r_AB_mag;
if (normalOverlapMag > 0)
{
//Particles in collision
vector rHat_AB = r_AB/(mag(r_AB) + VSMALL);
vector rHat_AB = r_AB/(r_AB_mag + VSMALL);
vector U_AB = pA.U() - pB.U();
......@@ -208,6 +214,15 @@ void Foam::PairSpringSliderDashpot<CloudType>::evaluatePair
rHat_AB
*(kN*pow(normalOverlapMag, b_) - etaN*(U_AB & rHat_AB));
// Cohesion force
if (cohesion_)
{
fN_AB +=
-cohesionEnergyDensity_
*overlapArea(dAEff/2.0, dBEff/2.0, r_AB_mag)
*rHat_AB;
}
pA.f() += fN_AB;
pB.f() += -fN_AB;
......
......@@ -34,6 +34,7 @@ Description
#include "PairModel.H"
#include "CollisionRecordList.H"
#include "mathematicalConstants.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
......@@ -67,6 +68,12 @@ class PairSpringSliderDashpot
//- Coefficient of friction in for tangential sliding
scalar mu_;
//- Cohesion energy density [J/m^3]
scalar cohesionEnergyDensity_;
// Switch cohesion on and off
bool cohesion_;
//- The number of steps over which to resolve the minimum
// harmonic approximation of the collision period
scalar collisionResolutionSteps_;
......@@ -129,6 +136,23 @@ public:
return volumeFactor_;
}
// Return the area of overlap between two spheres of radii rA and rB,
// centres separated by a distance rAB. Assumes rAB < (rA + rB).
inline scalar overlapArea(scalar rA, scalar rB, scalar rAB) const
{
// From:
// http://mathworld.wolfram.com/Sphere-SphereIntersection.html
return
mathematical::pi/4.0
/sqr(rAB)
*(
(-rAB + rA - rB)
*(-rAB - rA + rB)
*(-rAB + rA + rB)
*( rAB + rA + rA)
);
}
//- Whether the PairModel has a timestep limit that will
// require subCycling
virtual bool controlsTimestep() const;
......
......@@ -82,6 +82,7 @@ subModels
pairCollisionCoeffs
{
// Maximum possible particle diameter expected at any time
maxInteractionDistance 0.006;
writeReferredParticleCloud no;
......@@ -94,6 +95,7 @@ subModels
alpha 0.12;
b 1.5;
mu 0.52;
cohesionEnergyDensity 0;
collisionResolutionSteps 12;
};
......
......@@ -91,6 +91,7 @@ subModels
pairCollisionCoeffs
{
// Maximum possible particle diameter expected at any time
maxInteractionDistance 0.006;
writeReferredParticleCloud no;
......@@ -103,6 +104,7 @@ subModels
alpha 0.12;
b 1.5;
mu 0.52;
cohesionEnergyDensity 0;
collisionResolutionSteps 12;
};
......
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