Lagrangian Tracer Setup

The formulas used for Lagrangian tracking can be found in Lagrangian Tracking Module.

To set up the Lagrangian tracer feature:

1. Compile the code using the make command with -DTRACKING active in “Makefile”. (Review compiling instructions here)

2. In “input.txt”, specify:

   TRACER_FILE = tracers.txt
   

   ‘tracers.txt’ (you can use other names) is the file that contains the initial positions of particles.

3. In “tracers.txt”, specify:

   give a header  ! the program does not read
   196            ! number of tracers
   1.0            ! plot interval for output
   3.5500000e+02   4.7500000e+02   0.0000000e+00   0.0000000e+00
   3.5700000e+02   4.7500000e+02   0.0000000e+00   0.0000000e+00
   3.5900000e+02   4.7500000e+02   0.0000000e+00   0.0000000e+00
   3.6100000e+02   4.7500000e+02   0.0000000e+00   0.0000000e+00
   ...
   

The first line: give a header

The second line: give the number of tracers

The third line: give time interval for output

The following lines: specify x, y, 0, 0, where (x,y) are the inital positions of tracers (in meters).

Note

The particle position \((x,y)\) is specified at the central point of a cell, the same as other model variables such as \(u,v,\eta\) etc. The orgin (0,0) is at the central point of the bottom-left (south-west) corner cell.