Design Analysis and 3D Measurement of Diffusive Broadening in a Y-mixer

Artificial compressibility, characteristics-based schemes for variable-density, incompressible, multispecies flows: Part II. Multigrid implementation and numerical tests

“…Ismagilov et al [30] derived analytic solutions for the dependence of the diffusion front position on the distance from the inlets and found that the position of the diffusion front is proportional to x 1 2 in the middle of the channel and to x 1 3 near the wall. These results were found to be in good agreement with experiments [30,31], approximate models [32,33] and solutions of the diffusion equations based on Ôfro-zenÕ flow conditions [31], i.e., solving only the advection-diffusion equations for species transport for a prescribed flow field. In our numerical investigation we have considered both 2-D and 3-D flows at low Reynolds numbers typical for microfluidic applications, Re 2 [25,100], and for a fixed value of Peclet number Pe = 10 3 .…”

“…Ismagilov et al [30] analyzed the advection-diffusion equations for a fully developed three-dimensional flow and indicated that the diffusion front position power-law dependency on the streamwise direction (i.e., along the channel) varies from 0.5 in the middle of the channel to 1/3 near the channel wall. These results were found to be in agreement with both experimental data [30,31] as well as numerical solutions [31]. The latter were obtained by solving the Navier-Stokes equations for the flow field, which in turn is used to compute advection-diffusion equations for species transfer (decoupled solution).…”

“…In all the above applications, the characteristic microchannel dimensions are of order 10 2 lm which is still in the domain of continuum mechanics simulations [27]. The Reynolds numbers occurring in these applications range from Re ( 1 (flow sensors, heat sink channels, capillary tubes [35]), Re $ 10 À1 À10 2 (e.g., in diffusion broadening [31] and micromixers [34]) to Re > 10 3 (microvalves, micronozzles/pumps [35]). …”

Two-fluid mixing in a microchannel

“…Hence, the density, viscosity and diffusivity of the two fluids were assumed to be the same and to be constant during mixing. This assumption is commonly adopted for numerical testing of micromixers (Greiner et al, 2000). The mixing uniformities at different cross-sections in the three types of micromixer are shown in Fig.…”

Artificial compressibility, characteristics-based schemes for variable density, incompressible, multi-species flows. Part I. Derivation of different formulations and constant density limit

“…The development of advanced computational models for variable density flows is motivated by several application problems including chemical reactors [1,2]; multi-material mixing [3][4][5]; environmental flows [6]; combustion engineering [7]; biological flow and mass transport [8]; highly stratified flows [9]; interfaces between fluid of different density [10]; inertial confinement fusion [11]; and problems in astrophysics [12]. Depending on the application, variable density flows can feature low or high speeds, a range of spatial and time scales as well as large density and temperature gradients, which in association with fast chemical reaction rates can result in stiff numerical solutions and slow convergence rates.…”