3-D Groundwater Contaminant Transport

In collaboration with Greg Whiffen and Christine Shoemaker of the Dept. of Civil Engineering at Cornell University, we have applied ADIFOR to the TLS3D 3-D groundwater contaminant-transport code. TLS3D employs a Taylor least squares finite-element procedure to solve the unsteady advection diffusion equation.

We computed derivatives of the single-species contaminant concentrations at each node at time step t + 1 to the flow field velocity vectors at time step t on meshes ranging in size from 4 to 32 rectangular box elements, corresponding to 48 to 432 independent variables. We verified the derivatives computed by ADIFOR with central differences. However, ADIFOR-generated derivatives can be computed much faster. The table below shows the complexity of evaluation the model (labelled f(x)) and the speedup that ADIFOR achieves over one-sided divided differences.

 	   

To view the paper describing this application in detail, click here.

Argonne National Laboratory/Mathematics and Computer Science Division/ autodiff@mcs.anl.gov