耦合 DFBI 体

#include "uclib.h"

void calculateForce(Real*, int, CoordReal*, unsigned int*, CoordReal*);
void calculateMoment(Real*, int, CoordReal*, unsigned int*, CoordReal*);

void
USERFUNCTION_EXPORT uclib()
{
  /* Register user functions here */
  ucfunc(calculateForce, "PointSetProfile", "Calculate Force");
  ucarg(calculateForce, "Point", "Coord", sizeof(CoordReal[3]));
  ucarg(calculateForce, "Point", "BodyId", sizeof(unsigned int));
  ucarg(calculateForce, "Point", "BodyPosition", sizeof(CoordReal[3]));

  ucfunc(calculateMoment, "PointSetProfile", "Calculate Moment");
  ucarg(calculateMoment, "Point", "Coord", sizeof(CoordReal[3]));
  ucarg(calculateMoment, "Point", "BodyId", sizeof(unsigned int));
  ucarg(calculateMoment, "Point", "BodyPosition", sizeof(CoordReal[3]));
}

以下用户程序对耦合端点之间作用的弹簧进行建模。一个端点附加到体，另一个端点附加到环境或另一个体。

#include "uclib.h"

void USERFUNCTION_EXPORT
calculateForce(Real (*result)[3], int size, CoordReal (*position)[3], 
  unsigned int *bodyId, CoordReal (*bodyPosition)[3])
{
  CoordReal delta[3];
  Real stiffness = 20.;     /* Spring stiffness */
  int i, j;

  if (size != 2)    /* If the number of end points is unequal 2, do not execute the following coding. */
                    /* This if-block is essential for parallel simulations. The DFBI point */
		    /* set is filled with the two end points on the master node only. */

    return;

  for (j = 0; j < 3; ++j)   /* Compute force vectors at the end points */
  {
    delta[j] = position[1][j] - position[0][j];
    result[1][j] = -stiffness*delta[j]; /* Force at second end point */
    result[0][j] = -result[1][j];   /* Force at first end point */
  }
}

void USERFUNCTION_EXPORT
calculateMoment(Real (*result)[3], int size, CoordReal (*position)[3], 
  unsigned int *bodyId, CoordReal (*bodyPosition)[3])
{
  int i, j;

  for (i = 0; i < size; ++i)
    for (j = 0; j < 3; ++j)
      result[i][j] = 0.;    /* Calculate no additional moment. */
}