**1. NAME AND TITLE**

AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of Waste
Transport in an Aquifer System.

**2. CONTRIBUTOR**

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; IBM 3033.

**4. NATURE OF PROBLEM SOLVED.**

AT123D is developed to compute the temporal-spatial distribution of contaminant concentration
or temperature resulting from artificial input into aquifer systems. The assumptions include
homogeneous flow field, constant aquifer properties, and simple aquifer geometry.

**5. METHOD OF SOLUTION**

The advective-dispersion equation augmented with sorption, decay, and source/sink is solved
analytically by means of Green's function. This makes the solution applicable to one-, two-, and three-dimensional problems as desired. The solution is written in terms of convolution integrals of the
source/sink and boundary conditions and Green's functions. AT123D is developed to implement these
integrals.

**6. RESTRICTIONS OR LIMITATIONS**

Because it is an analytical solution, computer storage requirement is minimal. However, when the
dispersivity is very small, the convergence in evaluating the series is very slow causing excessive
computational time. Under such conditions, a warning message will appear in the output. The user
should then invoke the option of infinite depth or infinite width depending on the nature of the
problem.

**7. TYPICAL RUNNING TIME**

The sample problem computing the concentration distribution at 72 points for 100 time steps
required 7.6 seconds of CPU time on the IBM 3033.

**8. COMPUTER HARDWARE REQUIREMENTS**

AT123D is operable on the IBM 3033 computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The sample problem was executed on the IBM FORT H compiler.

**10. REFERENCE**

G. T. Yeh, "AT123D: Analytical Transient One-, Two-, and Three-Dimensional Simulation of
Waste Transport in the Aquifer System," ORNL 5602 (March 1981).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.2MB) DOS diskette which contains the source
code plus sample problem input and output.

**12. DATE OF ABSTRACT**

June 1982.

**KEYWORDS: ** ONE-DIMENSION; TWO-DIMENSIONS; COMPLEX GEOMETRY; WASTE
MANAGEMENT; NUCLIDE TRANSPORT; RADIOLOGICAL SAFETY