The effect of wall heating on instability of channel flow
A. Sameen,Rama Govindarajan +1 more
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In this article, the effect of wall heating or cooling on the linear, transient and secondary growth of instability in channel flow is conducted. But the authors do not consider the effects of wall cooling on channel flow.Abstract:
A comprehensive study of the effect of wall heating or cooling on the linear, transient and secondary growth of instability in channel flow is conducted. The effect of viscosity stratification, heat diffusivity and of buoyancy are estimated separately, with some unexpected results. From linear stability results, it has been accepted that heat diffusivity does not affect stability. However, we show that realistic Prandtl numbers cause a transient growth of disturbances that is an order of magnitude higher than at zero Prandtl number. Buoyancy, even at fairly low levels, gives rise to high levels of subcritical energy growth. Unusually for transient growth, both of these are spanwise-independent and not in the form of streamwise vortices. At moderate Grashof numbers, exponential growth dominates, with distinct Rayleigh-Benard and Poiseuille modes for Grashof numbers upto $\sim 25000$, which merge thereafter. Wall heating has a converse effect on the secondary instability compared to the primary, destabilising significantly when viscosity decreases towards the wall. It is hoped that the work will motivate experimental and numerical efforts to understand the role of wall heating in the control of channel and pipe flows.read more
Citations
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Journal ArticleDOI
Instabilities in Viscosity-Stratified Flow
TL;DR: In this article, a review highlights the profound and unexpected ways in which viscosity varying in space and time can affect flow and the most striking manifestations are through alterations of flow stability, as established in model shear flows and industrial applications.
Journal ArticleDOI
Effect of wall heating on turbulent boundary layers with temperature-dependent viscosity
TL;DR: In this article, the effect of viscosity stratification on the turbulence statistics and skin friction was investigated, and an empirical relation for temperaturedependent viscosities for water was adopted.
Journal ArticleDOI
Modulation of turbulence in forced convection by temperature-dependent viscosity
TL;DR: In this paper, the authors performed an extensive campaign based on pseudo-spectral direct numerical simulations of turbulent water channel flow in the Reynolds number parameter space and found that turbulence modifications are associated with changes in the rate at which energy is produced and dissipated near the walls.
Journal ArticleDOI
Delaying transition to turbulence in channel flow: revisiting the stability of shear-thinning fluids
TL;DR: In this article, the linear stability of shear-thinning fluids modelled by the Carreau rheological law is investigated and a viscosity stratification is considered as a possible mean to postpone the onset of transition to turbulence in channel flow.
References
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Book
CRC Handbook of Chemistry and Physics
TL;DR: CRC handbook of chemistry and physics, CRC Handbook of Chemistry and Physics, CRC handbook as discussed by the authors, CRC Handbook for Chemistry and Physiology, CRC Handbook for Physics,
Book
Spectral Methods in Fluid Dynamics
M. Y. Hussaini,Thomas A. Zang +1 more
TL;DR: Spectral methods have been widely used in simulation of stability, transition, and turbulence as discussed by the authors, and their applications to both compressible and incompressible flows, to viscous as well as inviscid flows, and also to chemically reacting flows are surveyed.
Book
Stability and Transition in Shear Flows
TL;DR: In this article, the authors present an approach to the Viscous Initial Value Problem with the objective of finding the optimal growth rate and the optimal response to the initial value problem.