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------------------------------------------------------------
revno: 3700
committer: Anton Gladky <gladky.anton@xxxxxxxxx>
timestamp: Mon 2013-09-23 19:17:34 +0200
message:
  Add Antypov2011 reference and some links in Hertz-Mindlin model.
modified:
  doc/references.bib
  pkg/dem/HertzMindlin.cpp


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=== modified file 'doc/references.bib'
--- doc/references.bib	2013-08-28 10:26:24 +0000
+++ doc/references.bib	2013-09-23 17:17:34 +0000
@@ -608,3 +608,14 @@
 	url = "http://www.sciencedirect.com/science/article/pii/S0378437199001831";,
 	author = "Y.C. Zhou and B.D. Wright and R.Y. Yang and B.H. Xu and A.B. Yu",
 }
+
+@article{Antypov2011,
+	author={D. Antypov and J. A. Elliott},
+	title={On an analytical solution for the damped Hertzian spring},
+	journal={EPL (Europhysics Letters)},
+	volume={94},
+	number={5},
+	pages={50004},
+	url={http://stacks.iop.org/0295-5075/94/i=5/a=50004},
+	year={2011}
+}

=== modified file 'pkg/dem/HertzMindlin.cpp'
--- pkg/dem/HertzMindlin.cpp	2013-09-07 19:40:12 +0000
+++ pkg/dem/HertzMindlin.cpp	2013-09-23 17:17:34 +0000
@@ -86,7 +86,7 @@
 	// en or es specified, just compute alpha, otherwise alpha remains 0
 	if(en || es){
 		Real logE = log((*en)(mat1->id,mat2->id));
-		contactPhysics->alpha = -sqrt(5/6.)*2*logE/sqrt(pow(logE,2)+pow(Mathr::PI,2))*sqrt(2*E*sqrt(R)); // (see Tsuji, 1992)
+		contactPhysics->alpha = -sqrt(5/6.)*2*logE/sqrt(pow(logE,2)+pow(Mathr::PI,2))*sqrt(2*E*sqrt(R)); // (see Tsuji, 1992), also [Antypov2011] eq. 17
 	}
 	
 	// betan specified, use that value directly; otherwise give zero
@@ -319,7 +319,7 @@
 	}
 	else if (useDamping){ // (see Tsuji, 1992)
 		Real mbar = (!b1->isDynamic() && b2->isDynamic()) ? de2->mass : ((!b2->isDynamic() && b1->isDynamic()) ? de1->mass : (de1->mass*de2->mass / (de1->mass + de2->mass))); // get equivalent mass if both bodies are dynamic, if not set it equal to the one of the dynamic body
-		cn = phys->alpha*sqrt(mbar)*pow(uN,0.25); // normal viscous coefficient
+		cn = phys->alpha*sqrt(mbar)*pow(uN,0.25); // normal viscous coefficient, see also [Antypov2011] eq. 10
 		cs = cn; // same value for shear viscous coefficient
 	}