Evaporation-induced convective transport in confined saline droplets

2022 ◽  
pp. 128256
Author(s):  
Nabajit Deka ◽  
Swarnava Saha ◽  
Susmita Dash
Keyword(s):  
Convective Transport

Mass Transport Modelling in Porous Media Using Delay Differential Equations

2006 ◽  
Vol 258-260 ◽  
pp. 586-591
Author(s):  
António Martins ◽  
Paulo Laranjeira ◽  
Madalena Dias ◽  
José Lopes
Keyword(s):  
Porous Media ◽  
Differential Equations ◽  
Mass Transport ◽  
Delay Differential Equations ◽  
Dispersion Model ◽  
Flow Characteristics ◽  
Convective Transport ◽  
Transport Modelling ◽  
Flow Field Characteristics ◽  
Delay Differential

In this work the application of delay differential equations to the modelling of mass transport in porous media, where the convective transport of mass, is presented and discussed. The differences and advantages when compared with the Dispersion Model are highlighted. Using simplified models of the local structure of a porous media, in particular a network model made up by combining two different types of network elements, channels and chambers, the mass transport under transient conditions is described and related to the local geometrical characteristics. The delay differential equations system that describe the flow, arise from the combination of the mass balance equations for both the network elements, and after taking into account their flow characteristics. The solution is obtained using a time marching method, and the results show that the model is capable of describing the qualitative behaviour observed experimentally, allowing the analysis of the influence of the local geometrical and flow field characteristics on the mass transport.

Laminar natural convection about an isothermally heated sphere at small Grashof number

1968 ◽  
Vol 34 (1) ◽  
pp. 163-176 ◽  
Author(s):  
Francis E. Fendell
Keyword(s):  
Natural Convection ◽  
Three Dimensional ◽  
Perturbation Expansion ◽  
Outer Sphere ◽  
Convective Transport ◽  
Convection Flow ◽  
Constant Density ◽  
Boussinesq Model ◽  
Grashof Number ◽  
Recirculating Flow

The flow induced by gravity about a very small heated isothermal sphere introduced into a fluid in hydrostatic equilibrium is studied. The natural-convection flow is taken to be steady and laminar. The conditions under which the Boussinesq model is a good approximation to the full conservation laws are described. For a concentric finite cold outer sphere with radius, in ratio to the heated sphere radius, roughly less than the Grashof number to the minus one-half power, a recirculating flow occurs; fluid rises near the inner sphere and falls near the outer sphere. For a small heated sphere in an unbounded medium an ordinary perturbation expansion essentially in the Grashof number leads to unbounded velocities far from the sphere; this singularity is the natural-convection analogue of the Whitehead paradox arising in three-dimensional low-Reynolds-number forced-convection flows. Inner-and-outer matched asymptotic expansions reveal the importance of convective transport away from the sphere, although diffusive transport is dominant near the sphere. Approximate solution is given to the nonlinear outer equations, first by seeking a similarity solution (in paraboloidal co-ordinates) for a point heat source valid far from the point source, and then by linearization in the manner of Oseen. The Oseen solution is matched to the inner diffusive solution. Both outer solutions describe a paraboloidal wake above the sphere within which the enthalpy decays slowly relative to the rapid decay outside the wake. The updraft above the sphere is reduced from unbounded growth with distance from the sphere to constant magnitude by restoration of the convective accelerations. Finally, the role of vertical stratification of the ambient density in eventually stagnating updrafts predicted on the basis of a constant-density atmosphere is discussed.

scholarly journals On interpreting studies of tracer transport by deep cumulus convection and its effects on atmospheric chemistry

2008 ◽  
Vol 8 (20) ◽  
pp. 6037-6050 ◽  
Author(s):  
M. G. Lawrence ◽  
M. Salzmann
Keyword(s):  
Atmospheric Chemistry ◽  
Large Scale ◽  
Deep Convection ◽  
Convective Transport ◽  
Advective Transport ◽  
Tracer Transport ◽  
Transport Models ◽  
Mass Fluxes ◽  
Split Treatment ◽  
The Mean

Abstract. Global chemistry-transport models (CTMs) and chemistry-GCMs (CGCMs) generally simulate vertical tracer transport by deep convection separately from the advective transport by the mean winds, even though a component of the mean transport, for instance in the Hadley and Walker cells, occurs in deep convective updrafts. This split treatment of vertical transport has various implications for CTM simulations. In particular, it has led to a misinterpretation of several sensitivity simulations in previous studies in which the parameterized convective transport of one or more tracers is neglected. We describe this issue in terms of simulated fluxes and fractions of these fluxes representing various physical and non-physical processes. We then show that there is a significant overlap between the convective and large-scale mean advective vertical air mass fluxes in the CTM MATCH, and discuss the implications which this has for interpreting previous and future sensitivity simulations, as well as briefly noting other related implications such as numerical diffusion.

Analysis of Vapor Evaporation Loss in Filling Gasoline into Tank

2011 ◽  
Vol 347-353 ◽  
pp. 372-375 ◽  
Author(s):  
Wei Qiu Huang ◽  
Feng Li ◽  
Shu Hua Zhao ◽  
Jing Zhong
Keyword(s):  
Mass Transfer ◽  
Experimental System ◽  
Pilot Scale ◽  
Convective Transport ◽  
Operating Conditions ◽  
Vapor Concentration ◽  
Air Mass ◽  
Evaporation Loss ◽  
Gas Space ◽  
Gasoline Evaporation

A pilot-scale experimental system of filling gasoline into a tank was built to investigate gasoline vapor-air mass transfer in the tank gas space and the vapor evaporation loss from the tank in different operating conditions. The results showed that the higher the location of filling pipe exit inside the tank, the quicker the speed of the filling gasoline, and the higher the initial vapor concentration in the tank gas space, then the more severe the vapor-air convective transport and the larger the gasoline evaporation loss rates.

scholarly journals An investigation on the degradation behaviors of Mg wires/PLA composite for bone fixation implants: influence of wire content and load mode

2021 ◽  
Vol 28 (1) ◽  
pp. 39-47
Author(s):  
Xuan Li ◽  
Yu Cong ◽  
Jisheng Sui ◽  
Xiaolong Li
Keyword(s):  
Lactic Acid ◽  
Dynamic Load ◽  
Degradation Rate ◽  
Convective Transport ◽  
Poly Lactic Acid ◽  
Mechanical Loss ◽  
Bone Fixation ◽  
Load Mode ◽  
Degradation Behaviors ◽  
Ph Decrease

Abstract Poly-lactic acid based biocomposite strengthened with magnesium alloy wires (Mg wires/PLA composite) is prepared for bone fixation implantation. The influence of wire content and load mode on the degradation performances of the composite and its components is studied. The result suggests the degradation of Mg wires could slow down the pH decrease originated from the degradation of PLA, while a relatively high wire content contributes to descend the degradation rate of Mg wire in the composite. Dynamic load significantly promotes the mechanical loss of the specimens. After 30 days immersion, the Sb retention is about 65%, 52% and 55%, respectively for pure PLA, the composite at 10 vol% and 20 vol% under dynamic load, comparing to 75%, 70% and 72% under no load. Moreover, dynamic load could further mitigate the degradation of Mg wires by increasing convective transport of acidic products out of the composite.

Numerical Prediction of Flow in a Nuclear Fuel Bundle With Various Turbulence Models

2002 ◽  
Author(s):  
Wang Kee In ◽  
Dong Seok Oh ◽  
Tae Hyun Chun
Keyword(s):  
Turbulent Flow ◽  
Nuclear Fuel ◽  
Turbulence Models ◽  
Convective Transport ◽  
Stress Model ◽  
Convergence Criteria ◽  
Mean Flow ◽  
Numerical Predictions ◽  
Viscosity Models ◽  
Fuel Bundle

The numerical predictions using the standard and RNG k–ε eddy viscosity models, differential stress model (DSM) and algebraic stress model (ASM) are examined for the turbulent flow in a nuclear fuel bundle with the mixing vane. The hybrid (first-order) and curvature-compensated convective transport (CCCT) schemes were used to examine the effect of the differencing scheme for the convection term. The CCCT scheme was found to more accurately predict the characteristics of turbulent flow in the fuel bundle. There is a negligible difference in the prediction performance between the standard and RNG k-ε models. The calculation using ASM failed in meeting the convergence criteria. DSM appeared to more accurately predict the mean flow velocities as well as the turbulence parameters.

Sign in / Sign up

Export Citation Format

Share Document