waveprobes.h

WAVEPROBES
- Example of usage given below

WAVEPROBES

This function uses the built in height function in basilisk to calculate the surface elevation at a given point x (or x and y in 3D). The probes lower and upper elevation must be specified in the probe_heightlimits array. Calculated heights from heights(f,h) is only available in cells close to the free surface, hence the wave probe is discretized using as the number of points for which the distance to the surface is calculated. the specifiec number of points are evenly distributed between the lower and upper values specified in . Finally the function will return the value from the point closest to the free surface.

For 3D, the sea surface is assumed to be in the xy-plane. i.e., the probes are assumed to be aligned with the z-axis

Author: Oystein Lande Date: 2017-09-30 Updated: 2018-09-05 corrected some unfortunate bugs and made it more userfriendly.

#include "heights.h"
vector h[];

Start off by defining a helpful function

// Get index of minimum value
int getIndexMinProbe(double arr[], int size) {

   int i;
   int iii = 0;
   double sum = arr[0];

   for (i = 0; i < size; ++i) {
      if (arr[i] < sum){
        sum = arr[i];
        iii = i;  
        }
   }
   return iii;
}

/* Waveprobe function for 2D simulations*/
#if dimension == 2
double wprobe(double xcoord,double probe_heightlimits[],int ssize){
	double yi_dist[ssize];
    double yi[ssize];
    double ycoord;

	  //int NN = sizeof(yi_dist) / sizeof(double);
	for (int ccc=0;ccc<ssize;ccc++){
			ycoord = probe_heightlimits[0]+((probe_heightlimits[1]-probe_heightlimits[0])/(ssize-1.0))*ccc; 
            Point point = locate(xcoord,ycoord);
		if (h.y[] != nodata) {  
			yi[ccc] = y + height(h.y[])*Delta;

			yi_dist[ccc] = abs(y - yi[ccc]);
		}
		else{
			yi_dist[ccc] = 999;
      yi[ccc] = -999;
		}
		      
	}    
    return yi[getIndexMinProbe(yi_dist,ssize)];    
}
#endif

Waveprobe function for 3D simulations

#if dimension == 3
double wprobe(double xcoord,double ycoord,double probe_heightlimits[],int ssize){
	double zi_dist[ssize];
    double zi[ssize];
    double zcoord;
	  //int NN = sizeof(yi_dist) / sizeof(double);
	for (int ccc=0;ccc<ssize;ccc++){
		zcoord = probe_heightlimits[0]+((probe_heightlimits[1]-probe_heightlimits[0])/(ssize-1.0))*ccc; 
        Point point = locate(xcoord,ycoord,zcoord); 
		if (h.y[] != nodata) {  
			zi[ccc] = z + height(h.z[])*Delta;
			zi_dist[ccc] = abs(z - zi[ccc]);
		}
		else{
			zi_dist[ccc] = 999;
      		zi[ccc] = -999;
		}
		      
	}    
    return zi[getIndexMinProbe(zi_dist,ssize)];    
}

#endif

Example of usage given below

// find wave elevation at position x = 0, and write it to file, every 0.05sec event waveprobe (t+=0.05;t<=MAXTIME) { heights( static FILE * fp0 = fopen(“waveprobe0.dat”, “w”); double ycoords[2] = {-0.05,0.05}; // defines the minimum and maximum y-value double yMax0 = wprobe(0.0,ycoords,5); // The last value in wprobe specifies how many discretization points which should be used in the given ycoords range.
// update file fprintf(fp0, “%g %g”,t,yMax0); fflush(fp0); }