Publications
40 results found
Saeed TI, Morrison JF, Mughal MS, 2014, Roughness effects on swept-wing crossflow transition in moderate free-stream turbulence, 29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014
An experimental investigation of swept-wing crossflow transition is carried out, focussing on the effects of chord Reynolds number and direct roughness element height (spaced at the critical crossflow wavelength) in a moderate-level disturbance facility. Flow quality measurements performed in the wind tunnel indicate turbulence intensities of u'rms=U∞ = 0:14% and v'rms=U∞ = 0:20%. The Reynolds numbers are Rec = 1:3 × 106 and Rec = 1:6 ×106. Despite the disturbance levels being indicative of travelling wave dominated crossflow, flow visualisation reveals that stationary crossflow is the dominant mode. Increased DRE height is shown through flow visualisation to advance transition, with boundarylayer velocity profiles showing mean-flow deformation and fluctuating-velocity spectra containing a high-frequency mode normally associated with stationary crossflow related secondary instability. Nevertheless, spectral information and unsteady disturbance profiles do indicate the travelling crossflow modes are excited, and that their disturbance amplitude increases with Reynolds number (as expected from linear stability theory) and with roughness height.
White AH, Hall P, Mughal MS, 2013, Numerical and Asymptotic Analysis of Gortler Vortices Generated by Surface Roughness, 11th International Conference of Numerical Analysis and Applied Mathematics (ICNAAM), Publisher: AMER INST PHYSICS, Pages: 289-292, ISSN: 0094-243X
Mughal SM, Ashworth R, 2013, Uncertainty Quantification Based Receptivity Modelling of Crossflow Instabilities Induced by Distributed Surface Roughness in Swept Wing Boundary Layers, 43rd AIAA Fluid Dynamics Conference
white AH, Hall P, Mughal MS, 2013, Numerical and asymptotic analysis of Gortler vortices generated by surface roughness, International Conference on Numerical Analysis and Applied Mathematics (ICNAAM) - New York USA
The linear growth of Görtler vortices is studied using both high Reynolds number asymptotic theory and numerical approaches. Growth rates are calculated by using two different numerical methods: The linearised Navier-Stokes equations for flow over a concave wall and the equivalent high Reynolds limit, resulting in a parabolic set of equations. Asymptotic expansions are posed for the high Görtler number limit and it is shown that at least two terms in the asymptotic expansion are needed in order to make quantitative comparisons to the growth rates calculated from the numerical routines.
Arthur M, Horton H, Mughal MS, 2009, Modeling of Natural Transition in Properly Three-Dimensional Flows, 39th AIAA Fluid Dynamics Conference, Publisher: American Institute of Aeronautics and Astronautics
The paper describes a method for viscous flow prediction which includes the predictionof transition onset location as an integral part of the calculation. The method is similar toothers in that it is based on stability analysis of the boundary layers but acknowledges thatsolutions of the Reynolds-averaged Navier-Stokes (RANS) equations yield boundary layersof inadequate accuracy when conventional mesh sizes are used. The boundary layers aretherefore recomputed to high accuracy by solving the laminar boundary layer equations.Transition onset locations determined by the stability analysis are passed back to the RANSsolver for further iterations. The method described in this paper differs from others in thatthe laminar boundary layer calculation is fully three-dimensional and the stability analysis isthrough the fully three-dimensional parabolised stability equations for compressible flow.Results are presented to illustrate the capability of the laminar boundary layer method andthe effectiveness of the method for solving the parabolised stability equations. In addition,preliminary validation results are presented from calculations of the viscous flow over theAFRL 1303 UCAV concept to demonstrate that the fully three-dimensional laminarboundary layer and stability analysis components can be combined successfully with aRANS method for calculating flows with natural transition.
Mughal MS, Hussaini YM, Goodrick SL, et al., 2007, Role of buoyancy and heat release in fire modelling, propagation, and instability, The fire environment--innovations, management, and policy
Mughal MS, 2006, Stability Analysis of Complex Wing Geometries: Parabolised Stability Equations in Generalised Non-Orthogonal Coordinates, 36th AIAA Fluid Dynamics Conference and Exhibit
Atkin CJ, Sunderland R, Mughal MS, 2006, Parametric PSE Studies on Distributed Roughness Laminar Flow Control, 3rd AIAA Flow Control Conference
Atkin CJ, Mughal MS, 2005, Parametric Studies on the Application of Distributed Roughness Elements for Laminar Flow Control, 35th AIAA Fluid Dynamics Conference and Exhibit
Mughal MS, 1998, Active control of wave instabilities in three-dimensional compressible flows, THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS, Vol: 12, Pages: 195-217, ISSN: 0935-4964
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