Scaling is an integral component of ecology and earth science. To date, the ability to determine the importance of air – water gas exchange across large spatial scales is hampered partly by our ability to scale the gas transfer velocity and stream hydraulics. Here we report on a metadata analysis of 563 direct gas tracer release experiments that examines scaling laws for the gas transfer veloci...

Analysis of non-laminar flows in coarse alluvial beds has a wide range of applications in various civil engineering, oil and gas, and geology problems. Darcy equation is not valid to analyze transient and turbulent flows, so non-linear equations should be applied. Non-linear equations are classified into power and binomial equations. Binomial equation is more accurate in a wide range of velocit...

The local solid flow structure of gas-solid bubbling fluidized bed was investigated to identify and characterize the particle clusters. Extensive mathematical calculations were carried out using the energy-minimization multi-scale (EMMS) approach for evaluating cluster properties including the velocity, the size and the void fraction of clusters in the dense phase of the bed. The results showed...

This study is concerned with the prediction of particles’ velocity in a dilute turbulent gas-solidboundary layer flow using a fully Eulerian two-fluid model. The closures required for equationsdescribing the particulate phase are derived from the kinetic theory of granular flows. Gas phaseturbulence is modeled by one-equation model and solid phase turbulence by MLH theory. Resultsof one-way and...

We give two examples of spiral galaxies that show non-circular gas motions in the inner kiloparsecs, from SAURON integral field spectroscopy. We use harmonic decomposition of the velocity field of the ionized gas to study the underlying mass distribution, employing linear theory. The higher order harmonic terms and the main kinematic features of the observed data are consistent with an analytic...

Recently, Squire & Hopkins (2017) showed any coupled dust-gas mixture is subject to a class of linear “resonant drag instabilities” (RDI). These can drive large dust-to-gas ratio fluctuations even at arbitrarily small dust-to-gas mass ratios μ. Here, we explore the RDI in the simple case where the gas satisfies neutral hydrodynamics and supports acoustic waves (ω2 = cs k 2). The gas and dust ar...

The occurrence of heterogeneous flow structures in gas-particle flows seriously affects the gas-solid contacting and transport processes in high-velocity gas-fluidized beds. Particles do not disperse uniformly in the flow but pass through the bed in a swarm of clusters. The so-called “core-annulus” structure in the radial direction and “S” shaped axial distribution of solids concentration chara...

Gas-liquid membrane contactors offer several practical advantages including high surface area per unit volume; independent control of gas and liquid velocities without any flooding, loading, weeping, or foaming, pre-determined gas–liquid interfacial area, membrane modules, capability of linear scale-up; low corrosion problems, and low operation and capital costs. Two common types of membrane co...

Gas holdup and bubble size are important parameters for simulation and designing in bubble column reactors. Because based on these parameters, the available gas-liquid interfacial area is defined for mass transfer. In this paper, the results of applying magnetic fields on the velocity field and volume fraction of gas holdup are reported. Hydrodynamics of the bubble column in the reactors is inv...

the main objective of this paper is to examine the effect of nanomaterials on mass transfer coefficient in bubble type absorption of carbon dioxide by experiment. the absorption process is carried out in a bubble column and in room temperature. mass transfer coefficient, saturated concentration of co2, and gas holdup are determined in this system. the kinds of nanomaterials, the concentrations ...