Testing constraint based rolling resistance
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with projected Gauss-Seidel - spherical rigid bodies, nonlinear hertz contact constraints, coulomb friction 

Implementation: granularBodySystem by Da Wang

NIT - number of iterations (50 to 500)
COEF - rolling resistance coefficient
timestep 0.01 s
particle diamater 0.01 m
particle mass density 2500 kg/m3
restitution 0
Youngs modulus 4x10^6 N/m2