In this paper an unstructured multigrid algorithm is used as an iterative solution procedure for the discrete equations arising from an implicit time discretisation of the unsteady Euler equations on tetra-hedral grids. To calculate unsteady ows due to oscillating boundaries , a novel grid movement algorithm is introduced, in which an elliptic equation with a nonlinear diiusion coeecient is use...

The numerical behavior of two implicit time-marching methods is investigated in solving two-dimensional unsteady compressible flows. The two methods are the second-order multistep backward differencing formula and the fourth-order multistage explicit first stage, single-diagonal coefficient, diagonally implicit Runge-Kutta scheme. A Newton-Krylov method is used to solve the nonlinear problem ar...

The complex and unsteady aerodynamics of vertical axis wind turbines (VAWTs) pose significant challenges for simulation tools. Recently, significant research efforts have focused on the development of new methods for analysing and optimising the aerodynamic performance of VAWTs. This paper presents an electric circuit model for Darrieus-type vertical axis wind turbine (DT-VAWT) rotors. The nove...

The present study demonstrates how the Genetic Algorithm (GA), coupled with the CFD solvers ARC2D for 2D and KTRAN for 3D problems, can successfully be applied to the airfoil and wing aerodynamic drag minimization. The geometry of airfoil and wing sections is represented by a B-spline curve. The actual values of the coordinates of the control nodes for the B-spline curve are designated as the d...

The space-time discontinuous Galerkin discretization of the compressible NavierStokes equations results in a non-linear system of algebraic equations, which we solve with a local pseudo-time stepping method. Explicit Runge-Kutta methods developed for the Euler equations are unsuitable for this purpose as a severe stability constraint linked to the viscous part of the equations must be satisfied...

This paper explores the use of sharkskin in improving aerodynamic performance aerofoils. A biomimetic analysis denticles was conducted and were incorporated on surface a 2-Dimensional (2D) NACA0012 aerofoil. The including drag reduction rate, lift enhancement Lift to Drag (L/D) rate for calculated at different locations along chord line aerofoil Angles Attack (AOAs) through Computational Fluid ...

Sediment abrasion may cause the removal of material and efficiency loss to hydraulic machinery (hydro-turbine, pump, etc.), which worsen internal flow endanger safe operation machines. As is caused by impact sediment on solid surface, movement particles determines wear intensity. To understand mechanism machinery, motion characteristics asymmetric solid–liquid two-phase in a sediment-laden arou...

In this case study, we examine the effect of airfoil shape/camber on formation and existence stall cells. A series experiments using a NACA0012 wing with trailing-edge flap has been carried out over range angles attack ( $11.5^\circ$ – $21^\circ$ ), $0^\circ$ , $5^\circ$ $10^\circ$ ) chord-length-based Reynolds numbers (100 000–500 000). The influence these parameters cell explored. Tufts have ...