Turbulent channel flow with stable stratification beyond the Oberbeck-Boussinesq assumptions: A DNS study

Stratified turbulent flows abound in environmental and industrial settings. Examples are atmospheric boundary layer flows, the transport of nutrients and organisms and the mixing of heat and salinity in the oceans, fluid flow in heat exchangers, and the transport of reactants and products in chemical reactions. These examples and many others...

Near wall coherence in wall-bounded flows and implications for flow control

Opposition-control of the energetic cycle of near wall streaks in wall-bounded turbulence, using numerical approaches, has shown promise for drag reduction. For practical implementation, real-time opposition control is only realizable if there is a degree of coherence between the turbulent velocities passing a sensor and the target point...

DNS of heat transfer in a turbulent channel flow over fractal roughness

Convective heat transfer finds applications in several domains of industry like heat exchangers, gas turbine blades, IC engine surfaces etc. The surfaces of these heat transfer applications are either naturally rough owing to manufacturing techniques or become rough over a period of time during operation. These rough surfaces usually contain...

Indirect estimation of mean vorticity from polarized emission of nanoparticles in turbulent duct flows

Optical measurement techniques are widely used in fluid mechanics to measure quantities like velocity, vorticity, and temperature. They are usually non-intrusive visualization techniques that provide a major advantage by not influencing the flow properties. Most of the developed measurement techniques estimate vorticity by computing the...

A heat transfer - friction analogy for fluids at supercritical pressure

A new friction-heat transfer analogy for the prediction of heat transfer to turbulent fluids at supercritical pressure is presented. This analogy is based on the observation that the predominent events that determine the turbulent heat flux known as hot ejections and cold sweeps have different thermophysical properties. This observation is...

Numerical Prediction of Flow Induced Vibrations in Nuclear Reactors through Pressure Fluctuation Modelling

Flow induced vibrations (FIV) is a known problem in nuclear reactors. The interaction between the turbulent flow of the coolants and the fuel rod bundles generates vibrations which are undesirable. These vibrations can be a major cause of fatigue failures, stress corrosion cracking and fretting wear of materials, which lead to stand-still costs....