Immersed Boundary Method for CFD Analysis of Moving Boundary Problems in OpenFOAM

Abstract

CFD simulation of hydraulic equipments involving moving boundary components is really challenging due to difficulty in maintaining a good quality mesh essential for obtaining accurate numerical solutions. To deal with these problems, commercial codes such as Ansys CFX provide the option of mesh morphing which must be used in conjunction with pre-defined multiple grid configurations to account for changing flow domain. In contrast to this approach, immersed boundary method (IBM) provides an attractive alternative in which the complex moving surface is immersed in a fixed Cartesian (or polyhedral) grid. We have developed an immersed boundary simulation tool-kit for moving boundary problems based on OpenFOAM. It requires the user to provide the definition of the immersed surfaces in STL (stereolithography) format, type of flow (internal/external) and motion (stationary, pre-defined or flow-induced) of the surface. Numerical simulations have been performed for selected test cases to assess the computational performance of the immersed boundary too-kit. Numerical results of flow over stationary as well as vibrating cylinders agree very well with available experimental and numerical results, and show that the immersed boundary simulations accurately capture the vortex shedding frequency and vortical structures for moving boundary problems.

Simulations of self-propelled anguilliform swimming using the immersed boundary method in OpenFOAM

“…The numerical results using the newly implemented IBM have been proven to match well with other experimental and numerical results (Singh, Nonaka, & Oh, 2015). The existing IBM in OpenFOAM has been used to solve rigid-bodied (6 degrees of freedom) problems, for example, flow around a fixed cylinder (Constant et al, 2016(Constant et al, , 2017 or flow around an oscillating cylinder (Singh et al, 2015). As a complementary validation, the accuracy of the existing IBM in the toolbox foam-extend 3.2 had been tested using the model of flow shedding around a fixed cylinder (Re = 185) in Appendix (A).…”

“…Thereafter, Constant et al (2016) and Constant et al (2017) introduced another implementation methodology using the discrete indirect-imposition method. The numerical results using the newly implemented IBM have been proven to match well with other experimental and numerical results (Singh, Nonaka, & Oh, 2015). The existing IBM in OpenFOAM has been used to solve rigid-bodied (6 degrees of freedom) problems, for example, flow around a fixed cylinder (Constant et al, 2016(Constant et al, , 2017 or flow around an oscillating cylinder (Singh et al, 2015).…”