Image made using the COMSOL Multiphysics® software and is provided courtesy of COMSOL.
An ink droplet is ejected through a nozzle and travels through air until it hits the target. The model can be used to understand the effect of the ink properties and the pressure profile at the nozzle on the drop velocity, drop volume, and the presence of satellite drops.
The Microfluidics Module brings you easily-operated tools for studying microfluidic devices. Important applications include simulations of lab-on-a-chip devices, digital microfluidics, electrokinetic and magnetokinetic devices, and inkjets. The Microfluidics Module includes ready-to-use user interfaces and simulation tools, so called physics interfaces, for single-phase flow, porous media flow, two-phase flow, and transport phenomena.
Microfluidic flows occur on length scales that are orders of magnitude smaller than macroscopic flows. Manipulation of fluids at the microscale has a number of advantages – typically microfluidic systems are smaller, operate faster, and require less fluid than their macroscopic equivalents.
Energy inputs and outputs are also easier to control (for example, heat generated in a chemical reaction) because the surface-to-area volume ratio of the system is much greater than that of a macroscopic system. In general, as the length scale of the fluid flow is reduced, properties that scale with the surface area of the system become comparatively more important than those that scale with the volume of the flow.
This is apparent in the fluid flow itself as the viscous forces, which are generated by shear over the isovelocity surfaces, dominate over the inertial forces. The Reynolds number (Re) that characterizes the ratio of these two forces is typically low, so the flow is usually laminar. In many cases, the creeping (Stokes) flow regime applies (Re«1). Laminar and creeping flows make mixing particularly difficult, so mass transport is often diffusion limited, but even in microfluidic systems diffusion is often a slow process. This has implications for chemical transport within microfluidic systems. The Microfluidics Module is designed specifically for handling momentum, heat, and mass transport with special considerations for fluid flow at the microscale.