An Explanation and Understanding of Aerodynamic Lift by Triple Deck Theory

An explanation of aerodynamic lift still is under controversial discussion as can be seen, for example, in a recent published article in Scientific American [1]. In contrast to an approach via integral conservation laws we here review an approach via the classical Kutta-Condition and its relation to boundary layer theory. Thereby we summarize known results for viscous correction to the lift coefficient for thin aerodynamic profiles and try to remember the work on triple-deck or higher order Boundary Layer theory, its connection to interactive boundary layer theory, viscous/inviscid coupling as implemented to well-known engineering code Xfoil. Finally we compare its findings to simple 2D numerical solution of full Navier Stokes equations (CFD)models. As a conclusion, a clearer definition of terms like understanding and explanation applied to the phenomenon of aerodynamic lift will be given.

Effects of Viscous Dissipation and Joule Heating on Micropolar Hybrid Nanofluid in a Stretching/Shrinking Channel including Thermal/Solar Radiation

This study aims to investigate the behavior of the micropolar hybrid nanofluid (Cu-TiO2) in a stretching and shrinking channel while maintaining a continuous laminar flow. External effects from magnetic field, thermal and solar radiation are also considered in the model. The governing differential (momentum, micro-rotation, and energy) equations are transformed into dimensionless forms via similarity transformations based on the boundary layer theory. The resulting ordinary differential equations are solved numerically using the fourth-order Runge-Kutta-Gill technique with the shooting method. The effects of nanoparticles transport on fluid flow and heat transfer are discussed and compared to the pure water case. The results are presented in tables or graphs such as velocity, temperature, angular-velocity profiles, and concentration.

Heat Transfer From a Concentrated Tip Source in Falkner-Skan Flow

The Falkner-Skan flow over a wedge is classic in boundary layer theory. We consider the heat or mass transfer from a source at the vertex of the wedge. The interactions of thermal boundary layer and momentum boundary layer lead to nonlinear similarity equations which are integrated numerically. There exists a mixing index which depends on the Prandtl number and the wedge opening angle. Attention is paid to special cases such as forced convection in Blasius flow past a semi-infinite plate and the Hiemenz stagnation flow normal to a plate.

Mathematical modeling of a submerged jet of electric wind

Technological processes of electro-gas dynamics of dispersed systems are based on charging and transporting dispersed raw material particles in a strong electric field of a corona discharge. It is accompanied by turbulent gas motion caused by momentum transfer of ions to gas molecules. This accompanying motion is called electric wind. It must be considered when calculating the trajectories of particles and devices design. In recent years, equipment is being developed, the operation of which is based on the direct use of electric wind. In most cases these studies are based on experimental research and empirical calculation formulas, therefore, to make the design and construction of this equipment science oriented, it is necessary to develop mathematical models and methods for calculating this phenomenon. The object of the research is a unipolar electric corona discharge of direct current between a negative corona wire and a flat electrode in the form of a mesh. The calculation of a turbulent jet of an electric wind is considered both within the framework of the boundary layer theory and in a full-scale formulation using the k- и k- turbulence models in the Comsol program. Two new solutions for the velocity field of a submerged flat jet of electric wind are found and compared. They are an analytical solution based on the boundary layer theory and a numerical solution in a full-scale formulation based on the Reynolds equation integration. The novelty of the solutions is that they are applied for a two-dimensional problem and consider the turbulent motion of gas. The phenomenon of electric wind is widely applied in modern technologies that allow electric and gas cleaning, disinfection, and water purification from organic impurities, as well as treatment and disinfection of surfaces and air which is especially important recently. In the case of jet spread of electric wind in a closed channel, the boundary layer approximation conditions are satisfied, and a self-similar solution can be used. In the case of an open jet, the calculation should be carried out in a full-scale formulation of the problem based on the numerical solution of the Reynolds equation.

Review of an Explanation of Aerodynamic Lift by Triple Deck Theory

Inspired from a recent article by Regis , earlier publised work of McLean , , and informal discussions much earlier with members of the Danish Technical University and KTH, Sweden we summarize known results for viscous correction to the lift coefficient for thin aerodynamic profiles. We thereby try to remember [d=1]theto work of on triple-deck or higher order Boundary Layer theory and compare it to simple 2D Computational Fluid Dynamic (CFD) models. As a conclusion, a clearer definition of terms like understanding and explanation applied to the phenomena of aerodynamic lift will be given.