We investigate both the type I and II modes of stationary instability within the boundarylayer flow over a rotating disk. Extending the work of previous studies we find that the flow can be stabilised via the introduction of shear-thinning non-Newtonian fluids. Laminar-flow profiles are determined from a generalised von Kármán similarity solution. An asymptotic study is presented in the limit o...

Wall-models are essential for enabling large-eddy simulations of realistic problems at high Reynolds numbers. The present study is focused on approaches that directly model the wall shear stress, specifically on filling the gap between models based on wall-normal ordinary differential equations (ODEs) that assume equilibrium and models based on full partial differential equations that do not. W...

Boundary-layer theory is crucial in understanding why certain phenomena occur. We start by reviewing steady and unsteady separation from the viewpoint of classical non-interactive boundary-layer theory. Next, interactive boundary-layer theory is introduced in the context of unsteady separation. This discussion leads onto a consideration of largeReynolds-number asymptotic instability theory. We ...

An unsteady, two-dimensional, hydro magnetic, laminar mixed convective boundarylayer flow of an incompressible, Newtonian, electrically-conducting and radiating fluid along a semi-infinite vertical permeable moving plate with heat and mass transfer is analyzed, by taking into account the effect of viscous dissipation. The plate moves with a constant velocity in the direction of fluid flow while...

Finite-time Lyapunov exponents and vectors are used to define and diagnose boundarylayer type, two-timescale behavior and to construct a method for determining an associated slow manifold when one exists. Two-timescale behavior is characterized by a slow-fast splitting of the tangent bundle for the state-space. The slow-fast splitting defined by finite-time Lyapunov exponents and vectors is int...

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Understanding the interactions between the land surface and the atmosphere is key to modelling boundarylayer meteorology and cloud formation, as well as carbon cycling and crop yield. In this study we explore these interactions in the exchange of water, heat and CO2 in a cropland– atmosphere system at the diurnal and local scale. To that end, we couple an atmospheric mixed-layer model (MXL) to ...

In this Simulation, supersonic combustion of hydrogen at Mach 3.12 has been presented. The combustor has a single fuel injection perpendicular to the main flow from the base. Finite rate chemistry model with K-ε model have been used for modeling of supersonic combustion. The pressure rise due to the combustion is not very high on account of global equivalence ratio being quite low. Within the i...

Experimental and numerical results have shown that two-dimensional surface roughness can stabilize a hypersonic boundary layer dominated by second-mode instability. It is sought to understand how this physical phenomenon extends from an airflow under a perfect gas assumption to that of a real gas. To these ends, a new high-order shock-fitting method that includes thermochemical nonequilibrium a...

In an excitable medium, wave breaks are essential for spiral wave formation. Although wave breaks can result from collisions between a wave and an obstacle, it is only when the resultant wave fragments separate from the obstacle ~wave-front–obstacle separation! that a spiral wave will begin to develop. We explored collisions between a piecewise linear obstacle and an incident wave front while v...