Fluid flow
filling of non-trivially shaped microfluidic channels.
The filling behavior of microfluidic channels is the result of a competition between surface tension forces and viscous resistance. The result of this competition can be analytically predicted for simple cases, such as a cylinder with a constant radius. For more complex geometries, a different approach is needed. Computational Fluid Dynamics (CFD) can be used to simulate the filling behavior of these channels and determine the filling time.
In this article two multiphase CFD simulations were performed for non-trivial channel cross sections (a rectangle and a trapezoid) using the Volume of Fluid (VoF) method. Using this approach, we were able to compare the filling times of the different geometries, which is an important design factor.
Fluid Dynamics
our approach.
A multiphase CFD simulation is set up using the Volume of Fluid method. Two phases are defined: a liquid phase (water) and a gas phase (air) with a surface tension between them. The flow is capillary-driven, meaning there is no driving pressure or velocity at the inlet or outlet. Instead, a wetting contact angle between the liquid and the wall is specified, which enables the liquid to slowly creep along the wall. At the start of the simulation the microfluidic channel is empty and the adhesion force causes the channels to slowly fill up, as seen in the figure on the right.
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Demcon multiphysics.
Demcon multiphysics is an engineering agency with high-end expertise in the area of heat transfer, fluid dynamics, structural mechanics, acoustics, electromagnetism and nuclear physics. We support clients from a wide variety of market sectors and help them achieve their goals in research and development with deep physical insights.
We combine fundamental physical knowledge from an analytical approach with Computer Aided Engineering (CAE) simulations tools from ANSYS, MATHWORKS, COMSOL, STAR-CCM+ and FLUKA to setup, execute, analyze and evaluate numerical simulations. The use of Computational Fluid Dynamics (CFD), Finite Element Analysis (FEM / FEA), Lumped Element Modelling (LEM), Computational Electromagnetics (CEM) and Monte Carlo simulations enables us to make a virtual prototype of your design. With these techniques we can simulate the fluid and gas flows, energy exchange, heat and mass transfer, stresses, strains and vibrations in structures and the interaction of electromagnetic fields with other physical aspects like heat generation. Simulation-driven product development increases the development efficiency and reduces the product development time. Our services can therefore fully support you in the designing phase, from idea up to prototype, from prototype to final design.
