drag.form

利用C

# Copyright (C) 2007 Anders Logg.
# Licensed under the GNU LGPL Version 2.1.
#
# First added:  2007-05-14
# Last changed: 2007-05-14
#
# This form defines the functional for computing the
# drag on a body.
#
# Compile this form with FFC: ffc -l dolfin Drag.form.

element = FiniteElement("Lagrange", "triangle", 1)

p = Function(element)
n = FacetNormal("triangle")
M = -p*n[0]*ds