Computational fluid dynamics application to aerospace science

Abstract

critical stability criterion for finite-difference approximation and addressed the issue of resolving hydrodynamic shock as early as 1944 and his more accessible article in the literature was published six years later (2,3) . Under the similar war time security restriction, the spherical blast wave computation by G. I. Taylor was also delayed for public release until 1950 (4) . These pioneering works were performed to meet an urgent engineering need which set a pattern of science and technology development for practical applications.Harlow and his colleagues developed the particle in cell(PIC) method based on a combination Lagrangian-Eulerian description of the fluid motion (5) . The PIC method has showed how well suited it was to study time-dependent and multi-dimensional fluid motion. The effectiveness of this method is demonstrated through the applications to shock interaction, supersonic wakes, and hypersonic sharp leading-edge flows. This method is still in use today for Magneto-hydrodynamic research. At the same time, Hirt made a lasting contribution to turbulent transport properties simulation by highlighting the numerical challenges and providing guidance for future research (6) . All these accomplishments were accompanied by exhaustive proof in order to illustrate the validity of the approximations and the numerical accuracy. This rigorous process actually established the standards for all future CFD algorithm and numerical procedure research. The detailed derivation of formulations and extensive discussions on computational accuracy and limits of applicability became the accepted standard in CFD research. During that time, all valuable information was largely unknown to the aerospace science community. ABSTRACTA brief narration on significant accomplishments in computational fluid dynamics (CFD) for basic research and aerospace application is attempted to highlight the outstanding achievements by scientists and engineers of this discipline. To traverse such a vast domain, numerous and excellent contributions to CFD will be unintentionally overlooked by the author's limited exposure. Nevertheless it is an ardent hope that the present abridged literature review will aid to reaffirm excellence in research and to identify knowledge shortfalls both in aerodynamics and its modeling and simulation capability. The future modeling and simulation technology needs, as well as potential and fertile research areas, are humbly put forth for consideration.

Thermo-Chemical Phenomena Simulation for Ablation

“…In Figure 5, the threedimensional result at eight-degree of angle of attack exhibits a significant 3-D relief effect which has not been resolved by all known previous investigations [17]. The pressure contour and the surface shear stress vector trace are present together; the post-shock expansion at the angle of attack condition is spreading into a very large lower pressure sector from the stagnation region indicating by the surface shear flow direction and the pressure contour.…”

“…In high-temperature air, the most important optical activity molecules are well known and they are; the transitions for O 2 (Schumann-Runge;  , C2 + , CN, CO, CO + add to a substantial amount of complexity to the electronic bands to be included into radiative heat transfer analysis [9][10][11][12]. According to the work by Laux et al [16,17], for blunt body with a reentry speed around 10 km/s and the strong absorption by C and CO has been detected in the vacuum ultraviolet (80 -200 nm) and ultraviolet spectra. The emission of cyanide (CN) has also been noted, as well as, a low intensity absorption by CO 2 within the boundary layer.…”

“…In all, the nonequilibrium radiation is responsible for 26% of the total radiation flux in the spectra of 80-600 nm. Some of these transition processes are not fully understood but become critical mechanisms for the radiative heat transfer process [1][2][3][4][5][6][7]16,17]. …”

“…The computation for radiation heat transfer is based on multi-group model in a given spectrum. Within the divided bandwidth of each spectral group, the averaged absorption coefficients are used including the wideband and narrow-band models of a spectrum, or by the Line-by-line integration over the full spectrum [14,16,17]. The equation of radiation intensity is solved in the divided band with frequency-independent spectral coefficients of emission and absorption.…”

“…Therefore the detailed of gaseous motion through the porous ablating material is relegated to the research results of ablative material. The heat transfer term q accommodates the heat flux by conduction, convection, as well as, radiation transfer according to the energy conservation equation, equations [4][5][6]16,17]. Finally, the normal stress component is designated as and it's the only tensoral stress component that can contribute to the work done by the gas media; the non-equilibrium gas, sublimating vapor, and pyrolysis gas of the ablating material.…”