The aspect ratio (Γ) dependence of the heat transfer (Nusselt number Nu in dimensionless form) in turbulent (two-dimensional) Rayleigh-Bénard convection is numerically studied in the regime 0.4≤Γ≤1.25 for Rayleigh numbers 10(7)≤Ra≤Ra(9) and Prandtl numbers Pr=0.7 (gas) and 4.3 (water). Nu(Γ) shows a very rich structure with sudden jumps and sharp transitions. We connect these structures to the ...

We present a three-pronged numerical approach to the dynamo problem at low magnetic Prandtl numbers P(M). The difficulty of resolving a large range of scales is circumvented by combining direct numerical simulations, a Lagrangian-averaged model and large-eddy simulations. The flow is generated by the Taylor-Green forcing; it combines a well defined structure at large scales and turbulent fluctu...

In this paper, a hybrid numerical flux scheme of low diffusion ECUSP (LDE) and HLL scheme is proposed by decomposing the cell-face normal vector. In the direction normal to shocks, the HLL scheme is applied to suppress carbuncles, in the other direction, the ECUSP scheme is implemented to keep low numerical diffusion. The new scheme with fifth-order WENO reconstruction is tested by using severa...

• The behaviour of the turbulent Prandtl number is investigated near a vertical surface. application machine learning method introduced for buoyancy-affected flow. developed data-driven algebraic models are shown to perform well wide range parameter space. ( Pr t ) flows surface as an extension study Gibson & Leslie, Int. Comm. Heat Mass Transfer , Vol. 11, pp. 73–84 (1984). By analysing locati...

• DNS database for low- Pr flows involving mixed aiding and opposing buoyant flow conditions. Effect of Re, , buoyancy on the turbulent field thermal transport. Ri Prandtl number, assessment analytic formulations. A direct numerical simulation (DNS) is presented heat transfer in a vertical channel Reynolds number Re τ = 150 640, 0.004, 0.025 0.71, with without forcing ( 0 0.15 or 0.21). The eff...

Turbulent convection at low Prandtl numbers is in many aspects still terra incognita on the parameter map. One reason for this fact that laboratory experiments turbulent regime are notoriously challenging as they require use of opaque liquid metals. These working fluids prevent application typical optical imaging techniques such particle image velocimetry. Recent by Grannan et al. ( J. Fluid Me...