There have been relatively few studies of turbulent collision rate sedimenting droplets in the context cloud physics, for which both gravitational settling and inertial effects must be simultaneously considered. In this study, direct numerical simulations (DNS) were used to study geometric rates droplets. Both Stokes drag law a nonlinear considered, but droplet–droplet local aerodynamic interactions not included. Typical droplet turbulence parameters convective clouds determine flow...

We present a pore-scale study of two-phase relative permeability in homogenous-wet porous media, and media altered to mixed-wet state. A Shan-Chen type multicomponent lattice Boltzmann (LB) model is employed determine fluid distributions permeability. Mixed-wet states are created by altering the wettability solid surfaces contact with nonwetting phase at end steady state simulation initially media. To ensure accurate representation fluid-solid interfacial areas, we compare LB results...

The effect of air turbulence on the geometric collision kernel cloud droplets can be predicted if effects two kinematic pair statistics modeled. first is average radial relative velocity and second distribution function (RDF). A survey literature shows that no theory available for predicting finite-inertia sedimenting in a turbulent flow. In this paper, developed, using statistical approach assuming gravitational sedimentation dominates motion before collision. weak-inertia limit, reveals...

Abstract A methodology for conducting direct numerical simulations (DNSs) of hydrodynamically interacting droplets in the context cloud microphysics has been developed and used to validate a new kinematic formulation capable describing collision rate efficiency turbulent air. The theoretical is formally same as recently geometrical finite-inertia, nonsettling particles. It shown that its application requires corrections because nonoverlap requirement. An approximate method correcting...

The collision efficiency of sedimenting cloud droplets in a turbulent air flow is key input parameter predicting the growth by collision–coalescence. In this study, was directly computed, using hybrid direct numerical simulation (HDNS) approach (Ayala et al 2007 J. Comput. Phys. 225 51–73). HDNS results show that turbulence enhances partly due to fact aerodynamic interactions (AIs) become less effective reducing relative motion presence background turbulence. level increase depends on...

Understanding the two-way interactions between finite-size solid particles and a wall-bounded turbulent flow is crucial in variety of natural engineering applications. Previous experimental measurements particle-resolved direct numerical simulations revealed some interesting phenomena related to particle distribution turbulence modulation, but their in-depth analyses are largely missing. In this study, channel flows laden with neutrally buoyant spherical simulated using lattice Boltzmann...

The paper describes application of the mesoscopic lattice Boltzmann (LB) method to simulations both single-phase turbulence and particle-laden which are maintained by a large-scale forcing. disturbance flows around finite-size solid particles resolved, providing opportunity study detailed interactions between fluid at particle–fluid interfaces. Specifically, nonuniform time-dependent stochastic forcing scheme is implemented within multiple-relaxation-time LB approach. statistics forced...

We study the dynamic and kinematic collision statistics of cloud droplets for a range flow Taylor microscale Reynolds numbers (up to 500), using highly scalable hybrid direct numerical simulation approach. Accurate results radial relative velocity (RRV) distribution function (RDF) at contact have been obtained by taking advantage their power-law scaling short separation distances. Three specific but inter-related questions addressed in systematic manner geometric collisions same-size (of...

A comprehensive investigation of the mechanical behavior and microstructural evolution carbon nanotube (CNT) continuous fibers under twisting tension is conducted using coarse-grained molecular dynamics simulations. The tensile strength CNT with random stacking found to be higher than that regular stacking. factor dominating response identified as individual stretching. simplified twisted fiber model studied illustrate structural mechanisms tension. Moreover, it demonstrated can reinforced...

Abstract. This paper discusses cloud simulations aiming at quantitative assessment of the effects turbulence on rain development in shallow ice-free convective clouds. Cloud fields from large-eddy (LES) applying bin microphysics with collection kernel enhanced by are compared to those standard gravitational kernel. Simulations for a range condensation nuclei (CCN) concentrations contrasted. Details how parameterized turbulent is used LES presented. Because disparity spatial scales between...

Within the context of heavy particles suspended in a turbulent airflow, we study effects gravity on acceleration statistics and radial relative velocity (RRV) inertial particles. The flow is simulated by direct numerical simulation (DNS) 2563 grid dynamics O(106) point-particle approach. For particles/droplets with radius from 10 to 60 μm, found that plays an important role particle statistics: (a) peak value variance appears both horizontal vertical directions at Stokes number about 1.2,...

The free-energy model can extend the lattice Boltzmann method to multiphase systems. However, there is a lack of models capable simulating multicomponent fluids with partial miscibility. In addition, existing cannot be generalized honor thermodynamic information provided by any equation state choice. this paper, we introduce where forcing term determined fugacity species, property that connects species pressure chemical potential calculations. By doing so, are able carry out simulations...

Abstract Due to mandates for the inclusion of engineering and computer science standards K-6 schools nationwide, there is a need understand how teacher educators can help develop preservice teachers’ (PSTs’) teaching self-efficacy in these areas. To provide experience learning coding, PSTs an instructional technology course were partnered with undergraduate students electromechanical systems teach robotics lessons fifth graders (10–11 year olds) over Zoom. A multi-case study approach...

Abstract Two formulations of an improved superposition method are proposed for studying droplet–droplet hydrodynamic interactions. The make explicit use the boundary conditions on surface two interacting droplets. described through a consistent and rigorous consideration relationship between drag force representation disturbance flows. It is demonstrated that much more accurate than original implementation method. Specifically, case Stokes flows, relative errors can be reduced by one order...

This study explores undergraduate engineering and education students’ perspectives on their interdisciplinary teams throughout the rapid transition to online learning instruction from a face-to-face virtual format. In this qualitative study, reflections focus groups three collaborations were analyzed using lens of Social Cognitive Theory. COVID-19 created dramatic change in environment such that most immediate direct impact experiences was environmental aspects Bandura’s triadic reciprocal...