Jasim Sadique
Johns Hopkins University
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Publication
Featured researches published by Jasim Sadique.
Physics of Fluids | 2015
Xiang Yang; Jasim Sadique; Rajat Mittal; Charles Meneveau
A new approach for wall modeling in Large-Eddy-Simulations (LES) is proposed and tested in various applications. To properly include near-wall physics while preserving the basic economy of equilibrium-type wall models, we adopt the classical integral method of von Karman and Pohlhausen (VKP). A velocity profile with various parameters is proposed as an alternative to numerical integration of the boundary layer equations in the near-wall zone. The profile contains a viscous or roughness sublayer and a logarithmic layer with an additional linear term that can account for inertial and pressure gradient effects. Similar to the VKP method, the assumed velocity profile coefficients are determined from appropriate matching conditions and physical constraints. The proposed integral wall-modeled LES (iWMLES) method is tested in the context of a pseudo-spectral code for fully developed channel flow with a dynamic Lagrangian subgrid model as well as in a finite-difference LES code including the immersed boundary method and the dynamic Vreman eddy-viscosity model. Test cases include a fully developed half-channel at various Reynolds numbers, a fully developed channel flow with unresolved roughness, a standard developing turbulent boundary layer flows over smooth plates at various Reynolds numbers, over plates with unresolved roughness, and a case with resolved roughness elements consisting of an array of wall-mounted cubes. The comparisons with data show that the proposed iWMLES method provides accurate predictions of near-wall velocity profiles in LES while, similarly to equilibrium wall models, its cost remains independent of Reynolds number and is thus significantly lower compared to existing zonal or hybrid wall models. A sample application to flow over a surface with truncated cones (representing idealized barnacle-like roughness elements) is also presented, which illustrates effects of subgrid scale roughness when combined with resolved roughness elements.
Boundary-Layer Meteorology | 2017
Jasim Sadique; Xiang Yang; Charles Meneveau; Rajat Mittal
We examine the effect of varying roughness-element aspect ratio on the mean velocity distributions of turbulent flow over arrays of rectangular-prism-shaped elements. Large-eddy simulations (LES) in conjunction with a sharp-interface immersed boundary method are used to simulate spatially-growing turbulent boundary layers over these rough surfaces. Arrays of aligned and staggered rectangular roughness elements with aspect ratio >1 are considered. First the temporally- and spatially-averaged velocity profiles are used to illustrate the aspect-ratio effects. For aligned prisms, the roughness length (
22nd AIAA Computational Fluid Dynamics Conference | 2015
Jasim Sadique; Xiang Yang; Charles Meneveau; Rajat Mittal
Journal of Fluid Mechanics | 2016
Xiang Yang; Jasim Sadique; Rajat Mittal; Charles Meneveau
z_\mathrm{o}
22nd AIAA Computational Fluid Dynamics Conference | 2015
Xiang I. Yang; Jasim Sadique; Charles Meneveau; Rajat Mittal
Bulletin of the American Physical Society | 2013
Xiang Yang; Jasim Sadique; Rajat Mittal; Charles Meneveau
zo) and the friction velocity (
Bulletin of the American Physical Society | 2013
Jasim Sadique; Xiang Yang; Charles Meneveau; Michael P. Schultz; Rajat Mittal
46th AIAA Fluid Dynamics Conference | 2016
Francois Cadieux; Jasim Sadique; Xiang I. Yang; Charles Meneveau; Rajat Mittal
u_*
Bulletin of the American Physical Society | 2015
Jasim Sadique; Xiang Yang; Charles Meneveau; Rajat Mittal
Bulletin of the American Physical Society | 2014
Xiang Yang; Jasim Sadique; Rajat Mittal; Charles Meneveau
u∗) increase initially with an increase in the roughness-element aspect ratio, until the values reach a plateau at a particular aspect ratio. The exact value of this aspect ratio depends on the coverage density. Further increase in the aspect ratio changes neither