Microfluidics and Nanofluidics

Mathematical Modeling and Computer Simulations of Nanofluid Flow with Applications to Cooling and Lubrication

“…Viscosity of nanofluids. Measurements of the rheological properties of nanofluids indicate that most nanofluids behave as Newtonian-fluid mixtures at low particle volume concentrations [103,104]. Particle concentration, size [105], shape [106], temperature, shear rate [107], surfactants, and pH have direct impacts on the viscosity of nanofluids.…”

“…In the single-phase approach, the suspended nanoparticles are assumed to be in thermal equilibrium with the liquid phase, and the relative velocity between the two phases can be neglected. The reasoning is that nanoparticles are so small, say, d p < 100 nm, that they closely follow the fluid streamlines, causing the nanofluid to behave like a homogeneous mixture [103]. Thus, the single-phase Navier-Stokes equations can be used with the effective thermo-physical properties of nanofluids, as follows:…”

“…It can be employed to assess the performance of thermal devices. The local entropy-generation rate (S gen in W/K) for convection heat transfer can be expressed as [103,128] S gen " S gen pthermalq`S gen pfrictionq.…”

“…where α T is the thermal accommodation coefficient with the value of α T " 1 [134]. The governing equations of the transport and phase change of the multicomponent droplet-vapor mixtures can be solved using computational fluid-particle dynamics (CF-PD) methods [103].…”

High Throughput Experimentation (HTE) Directed to the Discovery, Characterization and Evaluation of Materials

“…One route to a substantial scale reduction, microfluidics, is finding broadly expanding roles [21][22][23]. Reports catching the eye recently include application to: -directed evolution (where some $ 10 8 individual enzyme reactions were sampled in 10 h, using < 150 lL total reagent volume) [24]; -DNA sequence analysis [25]; -rapid screening of solubility (in which nL droplets with a gradual variation in solute concentration were passed along a channel with a temperature gradient, enabling 10 points of the solubility curve to be accumulated in < 1 h and with some 250 mL of solution);…”