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Improvements and corrections to AT123D code
Daniel K Burnell1, Barry H Lester, James W Mercer
1Tetra Tech GEO, Inc., Sterling, VA 20164, USA. dan.burnell@tetratech.com
Ground Water
|January 31, 2012
Summary
This study enhances the AT123D solute transport model to reduce numerical errors in complex simulations. The improved AT123D-AT code offers greater accuracy and efficiency for groundwater contamination modeling.
Area of Science:
- Environmental Science
- Hydrogeology
- Computational Science
Background:
- Semi-analytical solute transport models can suffer from significant numerical errors.
- High-frequency source terms and slow series convergence exacerbate these errors.
- Existing models may struggle with accuracy and computational efficiency in complex scenarios.
Purpose of the Study:
- To present and implement methods for correcting numerical errors in the AT123D code.
- To enhance the accuracy and computational efficiency of solute transport simulations.
- To enable accurate simulation of finite-duration (pulse) source releases.
Main Methods:
- Incorporation of a Romberg numerical integration scheme with error criteria and variable time stepping.
- Implementation of faster-converging series solution approximations for Green's functions.
- Modification to eliminate redundant calculations for improved computational efficiency.
Main Results:
- Reduced numerical errors in solute transport simulations, particularly for oscillatory source terms.
- Improved accuracy and computational efficiency for finite-depth aquifers.
- Successful simulation of finite-duration (pulse) source releases with the modified AT123D-AT code.
Conclusions:
- The enhanced AT123D-AT code provides a more accurate and efficient tool for solute transport modeling.
- The modifications address limitations of previous semi-analytical models.
- This advancement is crucial for reliable groundwater contamination and remediation studies.
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