This study describes the development, implementation, and evaluation of an effective curriculum for students to learn computational fluid dynamics (CFD) in introductory and intermediate undergraduate and introductory graduate level courses/laboratories. The curriculum is designed for use at different universities with different courses/laboratories, learning objectives, applications, conditions, and exercise notes. The common objective is to teach students from novice to expert users who are well prepared for engineering practice. The study describes a CFD Educational Interface for hands‐on student experience, which mirrors actual engineering practice. The Educational Interface teaches CFD methodology and procedures through a step‐by‐step interactive implementation automating the CFD process. A hierarchical system of predefined active options facilitates use at introductory and intermediate levels, encouraging self‐learning, and eases transition to using industrial CFD codes. An independent evaluation documents successful learning outcomes and confirms the effectiveness of the interface for students in introductory and intermediate fluid mechanics courses.

A combination of computational simulations (computational fluid dynamics) using two-and three-dimensional commercial flow solvers (FLUENT) and experimental flow visualization is used to show that low-amplitude oscillating distributed surface perturbations (dynamic roughness) can completely suppress leading-edge separation bubbles. Computational fluid dynamics simulations show that leading-edge short and long separation bubbles can be suppressed by dynamic roughness, causing the flow to tend toward an attached flow over the entire leading edge. It is shown that the suppression of the separation can be achieved using roughness that is a small fraction of the boundary thickness, providing that the roughness oscillation frequency is sufficiently large. The results also demonstrate an inverse relationship between roughness amplitude and frequency; as the maximum amplitude is increased, the associated frequency to maintain flow control decreased. These results from computational fluid dynamics are corroborated using smoke tunnel visualization experiments for the suppression of a leading-edge short and long separation bubble on a NACA 0012 airfoil with a leading-edge dynamic roughness skin.

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A two-dimensional Navier-Stokes algorithm is used to investigate unsteady, incompressible viscous ow past an airfoil leading edge with surface roughness that is characteristic of early-growth ice accretion. The roughness is added to the surface through the use of a Prandtl transposition and can generate both small-scale and large-scale roughness geometries. The algorithm is used to simulate steady or unsteady ow at constant angle of attack or pitch up corresponding to dynamic-stall conditions. Investigations of the dynamic stall show that some types of surface roughness can signi cantly alter the unsteady ow separation pattern and the formation of the dynamic-stall vortex. This includes both small-scale and large-scale roughness. Nomenclaturec = airfoil chord length f .» / = analytic expression for roughness geometry h = hump height K .t/ = angle-of-attack parameter l = leading-edge radius of curvature for parabola Re = Reynolds number P ® = pitch ratē = scale factor for governing equationś 0 ;´; Ń = normal coordinates » 0 ; »; N » = streamwise coordinates ¿ = pseudotime Ã; 9 = stream function !; Ä = vorticity Subscripts inv = inviscid value L ; R = left and right locations, respectively w = value at the wall 1 = freestream value

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This theoretical study is motivated by the experimental observations ( a ) on the thickening of a turbulent boundary layer compared with its laminar counterpart, ( b ) on the erupting tongue of fluid that forms the leading edge of a turbulent spot in a boundary layer, ( c ) on the wall-layer and mid-flow scales, and ( d ) on the slugs of vorticity that occur in the middle of turbulent channel and pipe flows. It appears that no previous rational explanation has been put forward for these experimental observations. The present tentative suggestions for ( a ), ( b ) and ( d ) centre on the existence of small-deficit fast-travelling zones of concentrated vorticity governed by the nonlinear Euler equations to leading order at high Reynolds numbers Re but crucially influenced by viscosity nevertheless. In the boundary-layer case these zones travel outside the original boundary layer and hence act to increase the effective boundary-layer thickness. The structure of such zones and their scales, governing equations and amplitude dependence are discussed for assumed planar boundary layers and channel flows and for three-dimensional pipe flows in turn. Allied with this, the theory addresses the closure of the amplitude-dependent neutral curve at high Reynolds numbers, the connection with other Euler-type flows and the possibility of delay in sublayer bursting, as well as aiming to give some guidance on nonlinear aspects of unsteady two- and three-dimensional computations for Euler and related flows. The aspects in ( c ) above, concerning the turbulent scales both of the thin wall layer ( O ( Re -1 In Re ), from a renormalizing and scale-cascade argument) and of the thicker mid-flow zone (containing the Kolmogorov microscale O ( Re -3/4 )) which lies between that layer and the extensive small-deficit outer zone, are also discussed tentatively in terms of their dynamics, leading to apparently good agreement with turbulent-flow experiments and empirical models, for those scales. Other qualitative comparisons are presented.

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