Fluid-fluid mixtures often possess a fine structure, or morphology, whose length scale is much smaller than the length scale over which the flow field and morphology vary. We define a microstructural variable called the area tensor, which describes the local morphology of such mixtures through volume-averaged size, shape, and orientation characteristics. The area tensor is equivalent to the int...

Entropic lattice Boltzmann methods have been developed to alleviate intrinsic stability issues of lattice Boltzmann models for under-resolved simulations. Its reliability in combination with moving objects was established for various laminar benchmark flows in two dimensions in our previous work Dorschner et al. [11] as well as for three dimensional one-way coupled simulations of engine-type ge...

Longitudinal heat conduction is an important parameter in the cryogenic field, especially in cryogenic heat exchangers. In the present work, the parasitic effect of tube wall longitudinal heat conduction on temperature measurement has been studied in cryogenic laminar hydrogen flow. The effects of various parameters such as wall cold end temperature, wall thermal conductivity, gas volumetric fl...

In a shallow channel, the flow transfers most of its momentum vertically. Based on this observation, one often neglects that is transferred across stream – core assumption shallow-water theory. context viscous flows, approximation referred to as ‘lubrication theory’, in which assumes shear stress exerted by fluid substrate over it flows proportional velocity. Here, we revise theory account for ...

The effect of fluid Prandtl number on the thermal characteristics flow at thermal-entry region a hydrodynamically fully developed turbulent channel friction Reynolds Re?=180 is investigated using direct numerical simulation. Four test cases with molecular numbers Pr = 0.71, 1, 3, 7 are considered. results confirm that in contrast to laminar flows, where entry length increases increase number, f...

We present a global, multi-scale model of fluid mixing in laminar flows, which describes the evolution of the spatial distribution of the microstructure in the mixture, for two fluids of identical viscosity with no interfacial tension. The flow domain is divided into cells, and large-scale variations in composition are tracked by following the cell-average concentrations of one fluid, using the...

We present a simple and effective ratcheted microfluidic mixer that uses contact charge electrophoresis (CCEP) of a micron-scale particle to rapidly mix nonpolar liquids. CCEP combines contact charging and electrostatic actuation to drive the continuous oscillatory motion of a conductive particle between two electrodes subject to a constant (DC) voltage. We show how this oscillatory motion can ...

Fluid mixing in small systems is difficult when the diffusion is a slow process compared to other relevant processes, and when the fluid dynamics is laminar, i.e., dominated by viscous forces. This is the prevailing situation in microfluidic systems. However, mixing is enhanced in chaotic flows. In this work we estimate and compute the mixing time in chaotic channel flows as tm = 1/(2σ) ln (Pe)...

Hydrostatic pressures were measured in cortical tubules, long loops of Henle, terminal collecting ducts, and in vasa recta in hamsters. In hydropenia, the loops of Henle and terminal collecting ducts provided the major fluid flow resistances, as judged by the location of hydrostatic pressure drops. In mannitol or saline diuresis, hydrostatic pressures in all tubular segments increased, but pres...