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	tSmall correction to fluid-particle coupling, extra particle no check in writeb…
	git clone git://src.adamsgaard.dk/sphere
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	---
	commit 269a809ba804db49d739b58442df78b437cf38f1
	parent 7e019763c23bf063f7ae4916bc03d404a648a135
	Author: Anders Damsgaard <[email protected]>
	Date: Fri, 4 Apr 2014 13:43:50 +0200

	Small correction to fluid-particle coupling, extra particle no check in writebin

	Diffstat:
	M python/sphere.py \| 28 +++++++++++++++-------------
	M src/navierstokes.cuh \| 27 ++++++++++++++-------------

	2 files changed, 29 insertions(+), 26 deletions(-)
	---
	diff --git a/python/sphere.py b/python/sphere.py
	t@@ -949,24 +949,26 @@ class sim:
	fh.write(self.x[i,:].astype(numpy.float64))
	fh.write(self.radius[i].astype(numpy.float64))

	- fh.write(self.xysum.astype(numpy.float64))
	+ if (self.np[0] > 0):
	+ fh.write(self.xysum.astype(numpy.float64))

	for i in range(self.np):
	fh.write(self.vel[i,:].astype(numpy.float64))
	fh.write(self.fixvel[i].astype(numpy.float64))

	- fh.write(self.force.astype(numpy.float64))
	-
	- fh.write(self.angpos.astype(numpy.float64))
	- fh.write(self.angvel.astype(numpy.float64))
	- fh.write(self.torque.astype(numpy.float64))
	-
	- # Per-particle single-value parameters
	- fh.write(self.es_dot.astype(numpy.float64))
	- fh.write(self.es.astype(numpy.float64))
	- fh.write(self.ev_dot.astype(numpy.float64))
	- fh.write(self.ev.astype(numpy.float64))
	- fh.write(self.p.astype(numpy.float64))
	+ if (self.np[0] > 0):
	+ fh.write(self.force.astype(numpy.float64))
	+
	+ fh.write(self.angpos.astype(numpy.float64))
	+ fh.write(self.angvel.astype(numpy.float64))
	+ fh.write(self.torque.astype(numpy.float64))
	+
	+ # Per-particle single-value parameters
	+ fh.write(self.es_dot.astype(numpy.float64))
	+ fh.write(self.es.astype(numpy.float64))
	+ fh.write(self.ev_dot.astype(numpy.float64))
	+ fh.write(self.ev.astype(numpy.float64))
	+ fh.write(self.p.astype(numpy.float64))

	fh.write(self.g.astype(numpy.float64))
	fh.write(self.k_n.astype(numpy.float64))
	diff --git a/src/navierstokes.cuh b/src/navierstokes.cuh
	t@@ -2279,14 +2279,13 @@ __device__ Float dragCoefficient(Float re)
	return cd;
	}

	-// Determine the fluid-particle interaction drag force based on the Ergun (195…
	-// equation for dense packed cells (phi <= 0.8), and the Wen and Yu (1966)
	-// equation for dilate suspensions (phi > 0.8). Procedure outlined in Shamy and
	-// Zeghal (2005) and Goniva et al (2010).
	-// Other interaction forces, such as the pressure gradient in the flow field
	-// (pressure force), particle rotation (Magnus force), particle acceleration
	-// (virtual mass force) or a fluid velocity gradient leading to shear (Saffman
	-// force).
	+// Determine the fluid-particle interaction drag force per fluid unit volume
	+// based on the Ergun (1952) equation for dense packed cells (phi <= 0.8), and
	+// the Wen and Yu (1966) equation for dilate suspensions (phi > 0.8). Procedure
	+// outlined in Shamy and Zeghal (2005) and Goniva et al (2010). Other
	+// interaction forces, such as the pressure gradient in the flow field (pressu…
	+// force), particle rotation (Magnus force), particle acceleration (virtual ma…
	+// force) or a fluid velocity gradient leading to shear (Saffman force).
	__global__ void findInteractionForce(
	Float* dev_ns_phi, // in
	Float* dev_ns_d_avg, // in
	t@@ -2294,7 +2293,6 @@ __global__ void findInteractionForce(
	Float3* dev_ns_v, // in
	Float3* dev_ns_fi) // out
	{
	-
	// 3D thread index
	const unsigned int x = blockDim.x * blockIdx.x + threadIdx.x;
	const unsigned int y = blockDim.y * blockIdx.y + threadIdx.y;
	t@@ -2324,7 +2322,8 @@ __global__ void findInteractionForce(
	const Float v_rel_length = length(v_rel);

	const Float not_phi = 1.0 - phi;
	- const Float re = (phidevC_params.rho_fd_avg)/devC_params.mu * v_rel_…
	+ const Float re = (phidevC_params.rho_fd_avg)/devC_params.mu
	+ * v_rel_length;
	const Float cd = dragCoefficient(re);

	Float3 fi = MAKE_FLOAT3(0.0, 0.0, 0.0);
	t@@ -2389,7 +2388,8 @@ __global__ void applyParticleInteractionForce(
	const unsigned int startidx = dev_cellStart[cellID];
	unsigned int endidx, i, origidx;

	- Float r, phi;
	+ Float r;
	+ //Float r, phi;
	Float3 fd;

	if (startidx != 0xffffffff) {
	t@@ -2402,11 +2402,12 @@ __global__ void applyParticleInteractionForce(
	__syncthreads();
	origidx = dev_gridParticleIndex[i];
	r = dev_x_sorted[i].w; // radius
	- phi = dev_ns_phi[idx(x,y,z)];
	+ //phi = dev_ns_phi[idx(x,y,z)];

	// this term could include the pressure gradient
	//fd = (-grad_p + fi/(1.0 - phi))(4.0/3.0M_PIrr*r);
	- fd = (fi/(1.0 - phi))(4.0/3.0M_PIrr*r);
	+ //fd = (fi/(1.0 - phi))(4.0/3.0M_PIrr*r);
	+ fd = fi(4.0/3.0M_PIrr*r);

	__syncthreads();
	dev_force[origidx] += MAKE_FLOAT4(fd.x, fd.y, fd.z, 0.0);