Theoretical investigation of capillary flow under gravity withmicro-bead suspension

摘要

In the present study, gravity assisted capillary transport of microbead suspension is investigated theoretically. An additional gravitational head from the reservoir which is placed at the top of the capillary is considered as pressure force at the inlet of capillary. The pressure field distribution at the inlet of capillary is deduced to calculate this inlet pressure force. The non-dimensional governing equation is derived by taking into account the surface, viscous and gravity forces which act on the fluid front. Presence of microbeads delays the capillary transport. It is observed from the numerical solution of the governing equation that, not only the aspect ratio of the capillary but the aspect ratio of reservoir also plays a vital role in the flow front transport in the capillary. Although higher fluid level in the reservoir has added advantage towards higher gravitational head, the resistance from reservoir makes the progress of the flow front movement slow at the beginning of the transport. The physical properties of the fluid also play an important role in deciding the progression fluid flow front.