Finite Element Method Based Multi Objective Topology Optimization for Enhanced Mixing With Reduced Pressure Drop

Rapid mixing in microchannels plays a significant role in chemical, biological and medical analysis fields. Microchannels are widely used for chemical and biochemical reactions because of their high surface to volume ratio. However, the rate of mixing of two or more chemical reagents is less as the flow through the micro-channel is highly laminar. Thus, two reactive fluids are predominantly parallel when they flow along the length of the channel. Generally, obstacles or surface modifications are made in the flow path which induces chaotic advection in the fluids. Considerable amount of research has been done in the past in developing different types of surface modifications to enhance the chaotic mixing. But, the intricate nature of fluid flow phenomenon makes it difficult to design the surface modification suitable to achieve the maximum rapid mixing. The present work aims at designing micromixers with the objective of obtaining rapid mixing with reduced pressure drop. A topology optimization algorithm is illustrated in the present manuscript for the design of optimal micromixer configuration. Finite element based optimization for surface modification of micromixer is developed using porosity of the channel as the control variable. In the present work, the optimisation solver works over two objectives. One is to increase the mixing in the channel and the second is to reduce the pressure drop. Numerical experiments are done to test the algorithm to obtain the optimal surface modification to achieve maximum rapid mixing between the two fluids. The results show that rapid mixing is achieved with the modified topology obtained using the code.