دانلود رایگان مقاله شبکه مدلسازی بولتزمن جریان دو فازی در دستگاه سیال میکرو الگودهی شده

Abstract

Recent advances for fabricating micro-featured architectures such as posts or pillars in fluidic devices provide exciting opportunities for multiphase flow management. Here we describe a novel, multiscale modeling approach for two-phase flows in microfeatured architectures developed within the Shan and Chen Lattice Boltzmann method. In our approach a fine scale is used to resolve the true microfeatured architecture, with a coarser scale used to model the gross geometry of the device. We develop the basic features of the approach and demonstrate its applicability to modeling retention times of droplets of a dispersed phase in an array of microposts – an architecture used in microfluidic reactors, bioreactors, and biomedical devises. Additionally we show that it is feasible to model the microfeatured geometry in a piecewise manner which includes extrapolating dispersed phase flow characteristics in the entire system based on simulations in smaller subdomains.

7. Conclusions and outlook

We presented a novel, multiscale modeling approach applicable for the two-phase flow in microscale devices with microfeatures applied within SC LBM. This approach was implemented within Shan and Chen Lattice Boltzmann model, and it was demonstrated by simulation of retention times of a dispersed phase flowing through microscale post array. The demonstration of the proposed multiscale modeling approach involves a coupling operator in the form of discrete vector fields applied atthe interface ofthe dispersed phase. Coupling operator was builtinto SC LBM as a source term, and defined as non-zero only at the interfacial nodes. Inclusion of the coupling operator did not cause instabilities and its impact on conservation properties was satisfactory. Tests with multiple coupling operators of various magnitudes and directions verified that a droplet behavior is sensitive to the directions and magnitudes of the applied operator. Multiscale modeling was applied to two model systems with rectangular posts of different spacing and dimensions. Simulation results were physically plausible which was confirmed through scaling of selected quantities from LB to physical units. Coupling operators were obtained for both setups. Operators provided the same retention times of the droplet in the geometrically uniform domain as in the post region of fully resolved domain including the posts. Developed coupling operators were also tested for their robustness yielding good accuracy in all investigated cases. We also demonstrated the concept of piecewise modeling of microarchitectures with posts. Rules for piecewise modeling were developed and supported with sufficiently accurate numerical results.