Swifts are aerodynamically sophisticated birds with a small arm and large hand wing that provides them with exquisite control over their glide performance. However, their hand wings have a seemingly unsophisticated surface roughness that is poised to disturb flow. This roughness of about 2% chord length is formed by the valleys and ridges of overlapping primary feathers with thick protruding ra...

Laminar-turbulent breakdown in a swept-wing boundary layer is typically caused by secondary instabilities of steady crossflow vortices (CFVs). So far, boundary-layer suction for laminar flow control in three-dimensional boundary layers has been applied to reduce the crossflow and thus the growth of the primary vortices only. We investigate the influence of strong, localized suction (pinpoint su...

Simultaneous heat and mass transfer in unsteady free convection flow with thermal radiation and thermal diffusion past an impulsively started infinite vertical porous plate subjected to a strong magnetic field is presented. The dimensionless governing equations for this investigation are solved analytically using two terms harmonic and non-harmonic functions. The influence of various parameters...

A Dynamic Data Driven Application Systems (DDDAS) methodology is developed for evaluation of fluid-thermal systems wherein a complete specification of the boundary conditions is not known a priori and experimental diagnostics are restricted to a limited region of the flowfield. The Closed Loop formulation of DDDAS is used whereby experiment and simulation are synergized in an iterative manner t...

Prediction of laminar-turbulent transition is a key factor in the design of the heat shield of vehicles (re-)entering a planetary atmosphere. To investigate the transition by means of numerical simulation, accurate and efficient computational methods are necessary. Here, the compressible Navier–Stokes equations are solved for a gas where properties such as specific heat, thermal conductivity, v...

One-way coupled Euler-Lagrangian simulations of bubbles in a spatially evolving turbulent boundary layer were performed. The simulation parameters were chosen to match an experiment by Sanders et al. (2006), though the Reynolds number of the boundary layer was lower than experiment. The bubbles were observed to migrate away from the wall, as observed in experiment. Budgets of the forces on the ...

In this paper, Least Square Method (LSM) and Differential Transformation Method (DTM) are used to solve the problem of laminar nanofluid flow in a semi-porous channel in the presence of transverse magnetic field. Due to existence some shortcomings in each method, a novel and efficient method named LS-DTM is introduced which omitted those defects and has an excellent agreement with numerical sol...

Similarity analysis is made of the three dimensional incompressible laminar boundary layer flow of general class of non-Newtonian fluids. This work is an extension of previous analysis by Na and Hansen (1967), where the similarity solution of laminar three dimensional boundary layer equations of Power-law fluids was investigated. For the present flow situation, it is observed that the similarly...

Wall transpiration, in the form of wall-normal suction or blowing through a permeable wall, is a relatively simple and effective technique to control the behaviour of a boundary layer. For its potential applications for laminar-turbulent transition and separation delay (suction) or for turbulent drag reduction and thermal protection (blowing), wall transpiration has over the past decades been t...

The effect of inlet conditions on the mixing of a passive scalar was investigated in a planar shear layer with inlet boundary layers that were laminar, tripped and naturally turbulent–transitional. Planar laser-induced fluorescence measurements of acetone were used to directly evaluate the shear layer structure, and were processed to determine probability density functions ~PDFs! of the mixture...