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------------------------------------------------------------
revno: 2207
committer: Sergei D. <sega@think>
branch nick: trunk
timestamp: Fri 2010-05-07 12:08:58 +0400
message:
  Add doc for utils.getViscoelasticFromSpheresInteraction
modified:
  py/_utils.cpp


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=== modified file 'py/_utils.cpp'
--- py/_utils.cpp	2010-05-06 15:26:07 +0000
+++ py/_utils.cpp	2010-05-07 08:08:58 +0000
@@ -429,7 +429,6 @@
 	py::def("bodyNumInteractionsHistogram",bodyNumInteractionsHistogram,bodyNumInteractionsHistogram_overloads(py::args("aabb")));
 	py::def("elasticEnergy",elasticEnergyInAABB);
 	py::def("inscribedCircleCenter",inscribedCircleCenter,(py::arg("v1"),py::arg("v2"),py::arg("v3")),"Return center of inscribed circle for triangle given by its vertices *v1*, *v2*, *v3*.");
-	py::def("getViscoelasticFromSpheresInteraction",getViscoelasticFromSpheresInteraction);
 	py::def("unbalancedForce",&Shop__unbalancedForce,(py::args("useMaxForce")=false),"Compute the ratio of mean (or maximum, if *useMaxForce*) summary force on bodies and maximum force magnitude on interactions. For perfectly static equilibrium, summary force on all bodies is zero (since forces from interactions cancel out and induce no acceleration of particles); this ratio will tend to zero as simulation stabilizes, though zero is never reached because of finite precision computation. Sufficiently small value can be e.g. 1e-2 or smaller, depending on how much equilibrium it should be.");
 	py::def("kineticEnergy",Shop__kineticEnergy,"Compute overall kinetic energy of the simulation as\n\n.. math:: \\sum\\frac{1}{2}\\left(m_i\\vec{v}_i^2+\\vec{\\omega}(\\mat{I}\\vec{\\omega}^T)\\right).\n\n.. warning::\n\n\tNo transformation of inertia tensor (in local frame) $\\mat{I}$ is done, although it is multiplied by angular velocity $\\vec{\\omega}$ (in global frame); the value will not be accurate for aspherical particles.\n");
 	py::def("sumForces",sumForces);
@@ -447,4 +446,5 @@
 	py::def("wireNone",wireNone,"Set :yref:`Shape::wire` on all bodies to False, rendering them as solids.");
 	py::def("wireNoSpheres",wireNoSpheres,"Set :yref:`Shape::wire` to True on non-spherical bodies (:yref:`Facets<Facet>`, :yref:`Walls<Wall>`).");
 	py::def("flipCell",&Shop::flipCell,(py::arg("flip")=Matrix3r(Matrix3r::Zero())),"Flip periodic cell so that angles between $R^3$ axes and transformed axes are as small as possible. This function relies on the fact that periodic cell defines by repetition or its corners regular grid of points in $R^3$; however, all cells generating identical grid are equivalent and can be flipped one over another. This necessiatates adjustment of :yref:`Interaction.cellDist` for interactions that cross boundary and didn't before (or vice versa), and re-initialization of collider. The *flip* argument can be used to specify desired flip: integers, each column for one axis; if zero matrix, best fit (minimizing the angles) is computed automatically.\n\nIn c++, this function is accessible as ``Shop::flipCell``.\n\n.. warning::\n\t This function is currently broken and should not be used.");
+	py::def("getViscoelasticFromSpheresInteraction",getViscoelasticFromSpheresInteraction,(py::arg("m"),py::arg("tc"),py::arg("en"),py::arg("es")),"Get viscoelastic interaction parameters from analytical solution of a pair spheres collision problem. \n\n:Parameters:\n\tm : float\n\t\tsphere mass\n\ttc : float\n\t\tcollision time\n\ten : float\n\t\tnormal restitution coefficient\n\tes : float\n\t\ttangential restitution coefficient.\n\n\n:return: \n\tdict with keys:\n\n\tkn : float\n\t\tnormal elastic coefficient computed as:\n\n.. math: k_n=\\frac{m}{t_c^2}\\left(\\pi^2+(\\ln e_n)^2\\right)..\n\n\n\tcn : float\n\t\tnormal viscous coefficient computed as:\n\n.. math: c_n=-\\frac{2m}{t_c}\\ln e_n..\n\n\n\tkt : float\n\t\ttangential elastic coefficient computed as:\n\n.. math: k_t=\\frac27\\frac{m}{t_c^2}\\left(\\pi^2+(\\ln e_t)^2\\right)..\n\n\n\tct : float\n\t\ttangential viscous coefficient computed as:\n\n.. math: c_t=-\\frac27\\frac{m}{t_c}\\ln e_t..\n\n\nFor details see Pournin, L., Liebling, T. M. & Mocellin, A. Molecular-dynamics force models for better control of energy dissipation in numerical simulations of dense granular media, Phys. Rev. E, 2001, 65, 01130");
 }