The Lubricated Immersed Boundary Method
Many real-world examples of fluid-structure interaction, including the intracellular, molecular motor-driven transport of transmembrane ion channels to neuronal synapses, involve the near-contact of elastic structures separated by thin layers of fluid. The separation of length scales between these lubrication layers and the typically much larger elastic objects poses significant computational challenges. Motivated by the challenge of resolving these multiscale problems, we introduce an immersed boundary method that uses elements of lubrication theory as a subgrid model to resolve thin fluid layers between immersed boundaries. We apply this method to flows of increasing complexity to show its increased accuracy compared to the classical immersed boundary method. We present preliminary simulations of cell suspensions, in which near-contact occurs through cell-wall, cell-cell, and intracellular interactions, to highlight the importance of accurately resolving these thin fluid layers.