[u, v, w, y]

c = 1.0 - y
wrate = rxn_rate(c)
fsd = sqrt (sqr(ddx(c)) + sqr(ddy(c)) + sqr(ddz(c)))

sd = ((d2dx(c) + d2dy(c) + d2dz(c)) * $rod + wrate) / fsd

nx = - ddx(c) / fsd
ny = - ddy(c) / fsd
nz = - ddz(c) / fsd

vn = u * nx + v * ny + w * nz

divn = ddx(nx) + ddy(ny) + ddz(nz)

absk = abs(divn)

fu = (vn + sd) * nx

lapc = d2dx(c) + d2dy(c) + d2dz(c)


t1 = sqr(fu')
t2 = sqr(absk')
t3 = sqr(divn')

avg { c, u, v, w, fsd, lapc, ddx_c, ddy_c, ddz_c, d2dx_c, d2dy_c, d2dz_c }

avg fsd { u, v, w, nx, ny, nz, t1, t2, fu, absk, divn, sd }