A numerical formulation for incompressible flows with stable stratification is developed using the framework of variational multiscale methods. In proposed formulation, both density and temperature are handled in a unified manner. The augmented weakly-enforced essential boundary conditions suitable applications involving moving domains, such as fluid–structure interaction. methodology tested three examples ranging from flow-physics benchmarks to simulation full-scale offshore wind-turbine...

Abstract Deep neural networks (DNNs) are implemented in Super‐Parameterized Energy Exascale Earth System Model (SP‐E3SM) to imitate the shortwave and longwave radiative transfer calculations. These DNNs were able emulate radiation parameters with an accuracy of 90–95% at a cost 8–10 times cheaper than original parameterization. A comparison time‐averaged fluxes prognostic variables manifested qualitative quantitative similarity between DNN emulation It has also been found that differences...

Abstract We present the first application of a fast super resolution convolutional neural network (FSRCNN) based approach for downscaling earth system model (ESM) simulations. Unlike other SR approaches, FSRCNN uses same input feature dimensions as low input. This allows it to have smaller convolution layers, avoiding over‐smoothing, and reducing computational costs. adapt improve reconstruction on ESM data, we term FSRCNN‐ESM. use high‐resolution (∼0.25°) monthly averaged output five...

Direct numerical simulation of flow past a sphere in stratified fluid is carried out at subcritical Reynolds number 3700 and $Fr=U_{\infty }/ND=1,2$ 3 to understand the dynamics moderately flows with $Fr=O(1)$ . Here, $U_{\infty }$ free stream velocity, $N$ background buoyancy frequency $D$ diameter. The unstratified consists separated shear layer that transitions turbulence, recirculation zone wake mean centreline deficit $U_{0}$ , decreases downstream distance as power law. With increasing...

Vortex dynamics in the flow past a sphere linearly stratified environment is investigated numerically. Simulations are carried out for with Reynolds number of Re = 3700 and several Froude numbers ranging from unstratified case Fr=∞ to highly wake Fr 0.025. Isosurface Q criterion used elucidate stratification effects on vortical structures near wake. Vortical tube-like show no preference their orientation. Moderate alters orientation streamwise but does not change form. In strongly cases...

Abstract In the present work, we report extensive GEANT4 simulations in order to study dependence of sensitivity Gd 3 Ga Al 2 O 12 :Ce (GAGG:Ce) scintillation crystal based detector on thickness crystal. All are made considering a thermalised Am-Be neutron source. The validated, qualitatively and quantitatively, by comparing simulated energy spectra values with those obtained from experimental measurements carried out using two different thicknesses our own experiment (0.5 mm mm) validated...

We use direct numerical simulations to investigate the energy pathways between velocity and magnetic fields in a rotating plane layer dynamo driven by Rayleigh–Bénard convection. The kinetic energies are divided into mean turbulent components study production, transport dissipation large- small-scale dynamos. This balance-based characterisation reveals distinct mechanisms for field generation dynamos, depending on nature of conditions imposed at boundaries. efficiency converting energy,...

The combined effects of the imposed vertical mean magnetic field ( $B_0$ , scaled as Alfvèn velocity) and rotation on heat transfer phenomenon driven by Rayleigh–Taylor (RT) instability are investigated using direct numerical simulations. In hydrodynamic (HD) case, strength Coriolis frequency $f$ ) increases, force enhances mixing fluids that dampens growth layer height $h$ reversible exchanges between fluids, leading to a reduction in transport, characterised Nusselt number $Nu$ )....

Direct numerical simulations (DNS) are performed to study the behaviour of flow past a sphere in regime high stratification (low Froude number $Fr$ ). In contrast previous results at lower Reynolds numbers, which suggest monotone suppression turbulence with increasing sphere, it is found that, below critical , induces unsteady vortical motion and turbulent fluctuations near wake. The wake quantified by computing energy spectra, equation, partition into horizontal vertical components,...

The effect of the rotation on turbulent mixing two miscible fluids small contrasting density, induced by Faraday instability, is investigated using direct numerical simulations. We quantify irreversible mixing, which depicts conversion available potential energy (APE) to background (BPE) through rate M. demonstrate that at lower forcing amplitudes, kinetic (t.k.e.) increases with an increase in Coriolis frequency f till (f/ω)2<0.25, where ω frequency, during sub-harmonic instability...

The primary focus of this study is to contrast the influence mean velocity profile with that initial turbulence on subsequent evolution and density fluctuations in a stratified wake. Direct numerical simulation used simulate following cases: (a) self-propelled momentumless turbulent wake, case SP50 canonical profile, (b) patch turbulence, TP1 same energy spectrum as (a), (c) TP2 different higher small-scale content. found be strongly dependent spectrum, e.g., TP2, kinetic substantially...

Direct numerical simulations are performed to study the evolution of a towed stratified wake subject external turbulence in background. A field isotropic is combined with an initial turbulent and simulated temporally evolving framework similar that Rind & Castro ( J. Fluid Mech. , vol. 710, 2012 p. 482). Simulations for whose level varies between zero moderate intensity up 7 % relative free stream integral length scale same order as turbulence. series carried out at Reynolds number 10...

Abstract Deep neural networks (DNNs) are developed from a data set obtained the dynamic Smagorinsky model to emulate subgrid‐scale (SGS) viscosity ( ν s g ) and diffusivity κ for turbulent stratified shear flows encountered in oceans atmosphere. These DNNs predict velocities, strain rates, density gradients such that evolution of kinetic energy budget variance terms is similar corresponding values original model. also compute ∼2–4 times quicker than resulting ∼2–2.5 acceleration entire...

Simulations of a coolant air flowing in heat exchanger with delta-winglet type vortex generators common-flow-up configuration have been performed to unveil the salient transfer characteristics. The is approximated as periodic rectangular channel heated walls and pair built-in tubes near inlet outlet. characteristics exchangers inlet, outlet, both outlet compared. Navier-Stokes equations together energy equation are solved employing unstructured finite volume method. simulations reveal...

We investigate the influence of rotation on onset and saturation Faraday instability in a vertically oscillating two-layer miscible fluid using theoretical model direct numerical simulations (DNS). Our analytical approach utilizes Floquet analysis to solve set Mathieu equations obtained from linear stability analysis. The solution comprises stable harmonic, subharmonic unstable regions three-dimensional diagram. find that Coriolis force delays responsible for growth mixing zone size at lower...

The heat transfer behaviour of convection-driven dynamos in a rotating plane layer between two parallel plates, heated from the bottom and cooled top, is investigated. At fixed rotation rate (Ekman number, $E=10^{-6}$ ) fluid properties (thermal magnetic Prandtl numbers, $Pr=Pr_m=1$ ), both dynamo convection (DC) non-magnetic (RC) simulations are performed to demarcate effect field on transport at different thermal forcings (Rayleigh $Ra=3.83\times 10^{9}\unicode{x2013}3.83\times 10^{10}$ )....

Abstract We perform numerical simulations to study the dynamics of entry hydrophobic spheres in a pool water. To track air-water interface during translation sphere water, we use volume fluid model. The continuum surface force method computes tension force. represent properties, wall adhesion terms static contact angle. with different diameters and impact speeds sphere. Our capture formation types air cavities, pinch-offs these other finer details similar experiments performed at same...

Rapidly rotating convection-driven dynamos are investigated under different kinematic and magnetic boundary conditions using DNS. At a fixed rotation rate, represented by the Ekman number $E=5\times10^{-7}$, thermal forcing is varied from 2 to 20 times its value at onset of convection ($\mathcal{R}=Ra/Ra_c=2-20$), keeping fluid properties constant ($Pr=Pr_m=1$). The statistical behavior, force balance heat transport characteristics depend on that dictate both layer interior dynamics....

The impact of a heavier droplet into deep pool lighter liquid is investigated using three-dimensional numerical simulations. Unprecedented to any simulations, we demonstrate that the droplets can hang from surface tension. phenomenon and evolution as function its size release height are explored. A theoretical model also formulated understand role different forms energies associated with hanging droplet. We further solve force balance equations for analytically results obtained our...

We perform three-dimensional numerical simulations to understand the role of viscous fingering in sweeping a high-viscous fluid (HVF). These fingers form due injection low-viscous (LVF) into porous media containing fluid. find that HVF depends on different parameters such as velocity (U0) LVF, ease diffusion (D), and logarithmic viscosity ratio LVF ℜ. The two-phase Darcy's law module COMSOL Multiphysics is used simulate cases with varying parameters. At high values U0 ℜ lower D, grow...

An innovative \textit{deep learning} approach has been adopted to formulate the eddy-viscosity for large eddy simulation (LES) of wall-bounded turbulent flows. A deep neural network (DNN) is developed which learns evaluate from a dataset generated channel flow at friction Reynolds number $Re_τ = 395$ using Dynamic Smagorinsky subgrid-scale model. Later this DNN employed predict grid configurations and $590$. The statistics computed based LES model show an excellent match with direct...

This study shows an implementation of neutron-gamma pulse shape discrimination (PSD) using a two-dimensional convolutional neural network. The inputs to the network are snapshots unprocessed, digitized signals from BC501A detector. By exposing detector Cf-252 source, neutron and gamma were collected create training dataset. realistic datasets created data-driven approach for labeling signals, having classified pulses. Our algorithm was able successfully differentiate neutrons gammas with...