In time, more advanced three-dimensional Panel Codes were developed at Boeing (PANAIR, A502), Lockheed (Quadpan), Douglas (HESS), McDonnell Aircraft (MACAERO), NASA (PMARC) and Analytical Methods (WBAERO, USAERO and VSAERO ). The first lifting Panel Code (A230) was described in a paper written by Paul Rubbert and Gary Saaris of Boeing Aircraft in 1968. Their method itself was simplified, in that it did not include lifting flows and hence was mainly applied to ship hulls and aircraft fuselages. This method discretized the surface of the geometry with panels, giving rise to this class of programs being called Panel Methods. The first paper with three-dimensional model was published by John Hess and A.M.O. Fromm's vorticity-stream-function method for 2D, transient, incompressible flow was the first treatment of strongly contorting incompressible flows in the world. From 1957 to late 1960s, this group developed a variety of numerical methods to simulate transient two-dimensional fluid flows, such as particle-in-cell method, fluid-in-cell method, vorticity stream function method, and Harlow, who is widely considered one of the pioneers of CFD. Probably the first work using computers to model fluid flow, as governed by the Navier–Stokes equations, was performed at Los Alamos National Lab, in the T3 group. The computer power available paced development of three-dimensional methods. In fact, early CFD calculations during the 1940s using ENIAC used methods close to those in Richardson's 1922 book. Although they failed dramatically, these calculations, together with Richardson's book Weather Prediction by Numerical Process, set the basis for modern CFD and numerical meteorology. One of the earliest type of calculations resembling modern CFD are those by Lewis Fry Richardson, in the sense that these calculations used finite differences and divided the physical space in cells. Two-dimensional (2D) methods, using conformal transformations of the flow about a cylinder to the flow about an airfoil were developed in the 1930s. Historically, methods were first developed to solve the linearized potential equations. Finally, for small perturbations in subsonic and supersonic flows (not transonic or hypersonic) these equations can be linearized to yield the linearized potential equations. Further simplification, by removing terms describing vorticity yields the full potential equations. These equations can be simplified by removing terms describing viscous actions to yield the Euler equations. The fundamental basis of almost all CFD problems is the Navier–Stokes equations, which define many single-phase (gas or liquid, but not both) fluid flows. Although CFD has a widespread real-world applications across many industries, it is difficult to master, hence, many companies overcome this knowledge barrier by engaging CFD consultants.Ī simulation of the Hyper-X scramjet vehicle in operation at Mach-7 A final validation is often performed using full-scale testing, such as flight tests.ĬFD is applied to a wide range of research and engineering problems in many fields of study and industries, including aerodynamics and aerospace analysis, hypersonics, weather simulation, natural science and environmental engineering, industrial system design and analysis, biological engineering, fluid flows and heat transfer, engine and combustion analysis, and visual effects for film and games. In addition, previously performed analytical or empirical analysis of a particular problem can be used for comparison. Initial validation of such software is typically performed using experimental apparatus such as wind tunnels. Ongoing research yields software that improves the accuracy and speed of complex simulation scenarios such as transonic or turbulent flows. With high-speed supercomputers, better solutions can be achieved, and are often required to solve the largest and most complex problems. Computers are used to perform the calculations required to simulate the free-stream flow of the fluid, and the interaction of the fluid ( liquids and gases) with surfaces defined by boundary conditions. Computational fluid dynamics ( CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows.
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