PSR-0573 SAEROSA.

1. NAME OR DESIGNATION OF PROGRAM:  SAEROSA.

3. DESCRIPTION OF PROGRAM OR FUNCTION

SAEROSA solves the dynamic aerosol coagulation and deposition problem with arbitrary computational precision under a variety of conditions. The code includes numerous user-selectable coagulation kernels, alone or in combinations, and permits an arbitrary initial size distribution. Many parameter combinations and what-if scenarios under user control are possible. The output gives the particle size distribution suspended in the carrier fluid initially and after the desired aerosol aging time in terms of both differential and integral aerosol volume concentrations. An auxiliary routine designed for the Mac OSX environment provides plotting capability. The output can be further processed by e.g., spreadsheets.

The code has been benchmarked against three computer models, including MAEROS, and analytical models with excellent agreement. The test cases also included scenarios where previously published computational coagulation models lack capabilities or exhibit numerical instabilities. These included narrow, delta function, and non-lognormal initial size distributions, and further conditions, such as the presence of simultaneous coagulation mechanisms, including electrostatic effects, spanning multiple flow-regimes.

4. METHODS

The Smoluchowski integro-differential equation for coagulation dynamics with deposition is solved using the sectional method with arbitrary size boundaries via a 5th-6th order Runge-Kutta-Verner scheme with adaptive time steps and error control.  The code employs exact formulations based on multi-precision arithmetic for the description of some of the frequently occurring simultaneous coagulation kernels. Surface deposition is treated using boundary layer theory.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Currently the maximum number of aerosol sections is 150, which is satisfactory for nearly all practical problems. It can be easily increased but the code then requires recompilation. The plotting utility can handle up to 50 sections.

6. TYPICAL RUNNING TIME

Running time varies depending on the number of sections and the type of the coagulation mechanism on a modern computer.  All test problems ran in less than one minute.

8. RELATED OR AUXILIARY PROGRAMS

GROUPS (Linux and MacOS versions only) computes the particle section boundaries from given minimum and maximum particle diameters.

SRPLOT (MacOS computers using INTEL Environment only) reads the SAEROSA output file and plots both the initial and final aerosol size distributions.

- E. Sajo and J. Geng, H Park:
SAEROSA: Single-Species Aerosol Coagulation and Deposition with Arbitrary Size
Resolution (April 2012)

11. HARDWARE REQUIREMENTS

The authors have tested SAEROSA on MS Windows, Linux-based Intel chips, Sun Solaris, and on Mac OS-X environments running on both PPC and Intel cores. Executables are provided for Mac OSX-Intel, MS Windows, and Linux systems.

13. SOFTWARE REQUIREMENTS

A Fortran compiler is required to compile the source code.  Minor changes may be required for code compilation.  SAEROSA is written in Fortran 77 and 95. Current versions have been compiled with Intel Fortran on Linux, Absoft 10.2 on Mac OSX-Intel, and Intel Fortran on MS Windows. Executables for these respective operating systems are provided with the distribution.

15. NAME AND ESTABLISHMENT OF AUTHORS

Contributed by: Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, USA
Developed by:   University of Massachusetts Lowell, Radiological Program,
                Lowell, MA, USA
                Los Alamos National Laboratory, Los Alamos, NM, USA
                Louisiana State University, Baton Rouge, LA, USA

precompiled executables for Linux, MacOS and Windows systems
source code
sample problems
documentation