Continuous growth of computing power strongly encourages engineers to
rely more on computational
fluid dynamics for the design and testing of new
technological solutions. The fast development of these new tools goes along
with the increasing availability of high-performance computers, which are necessary
to simulate realistic industrial applications. The presented immersed
boundary (IB) method is applicable to simple and complex geometries with
static and moving boundaries, where
fluids interact with the solid structures.
The formulation of the method is based on the Eulerian and Lagrangian principles
and its key characteristics are its simple formulation and computational
efficiency. Furthermore the nature of the method allows the simulations of
flows in complex geometries without having to generate complex meshes. The
spatial discretization is based on a fixed Cartesian mesh for the Eulerian variables
and boundary movements are tracked with Lagrangian particles. Large-
Eddy simulations of flows in simple and complex geometries demonstrate the
performance of the applied immersed boundary method. Simple cases include
the simulation of an isothermal pipe flow and the flow around a sphere. In
the first instance, the fluid flows around a static sphere. In the second case
the sphere moves relative to the grid for identical flow conditions. Simulations
of complex geometries include the investigation of an isothermal and reactive
opposed jet flow with perforated and fractal grids. The simulations require
cell sizes near the resolution of direct numerical simulations. The injection
phase of a piston-cylinder arrangement, assuming constant pressure, is also investigated
with the proposed IB method. Good statistical results for first and
second moments are achieved for all investigated cases, although the applied
grids have to be fine enough to accurately resolve the wall shear stresses. In
addition, the concept of using Lagrangian particles has been applied to immiscible
flows. Particles are used to improve the accuracy of scalar transport and
initial results of simple, two-dimensional test cases are presented.