Development of an object-oriented compressible viscous MHD code

Abstract

The focus of this paper is on the techniques for converting a Fortran 77 2-D MHD code into an object-oriented code using Sun's Java. The MHD code solves the 2-D compressible viscous magnetohydrodynamics equations with a bitemperature model and a variable conductivity model. The equations are solved in generalized coordinates using a modified four-stage Runge-Kutta time intregation scheme with a second order accurate spatial discretization. A symmetric Davis-Yee Total Variation Diminishing (TVD) flux limiter is employed to dampen the oscillations in the shock regions. The Fortran code is converted into the object-oriented Java code by employing primitive data type. The conversion is accomplished by carefully designing the classes and choosing the exact data type to suit the application. The static methods are developed to reduce the memory requirements. Both the Fortran and Java code are employed to compute the effect of magnetic field on a weakly ionized gas in a scramjet inlet moving at hypersonic speed. Both the Fortran and Java code produce identical results as should be the case. 1 Graduate Research Assistant 2 Bloomfield Distinguished Professor and Executive Director, Fellow AIAA 3 Postdoctoral Research Associate, Member AIAA © by the authors NOMENCLATURE Q field vector E flux vector component in the jc-direction F flux vector component in the -direction x Cartesian coordinate y Cartesian coordinate p density u velocity component in the jc-direction v velocity component in the y-direction M> velocity component in the z-direction V velocity vector Bx magnetic field component in the xdirection By magnetic field component in the ydirection Bz magnetic field component in the zdirection p static pressure Pi ionic pressure pa neutral atom pressure pe electronic pressure Po Pa+Pi Y. specific heat ratio of ionic gas ye specific heat ratio of electron gas y0 specific heat ratio of (ion + neutral atom) gas Se electron entropy ^ et total energy^Der fhiit mass cs speed of sound Vox Alfven wave velocity in the x-direction Vay Alfven wave velocity in the >>-direction American Institute of Aeronautics and Astronautics