An efficient ghost-cell immersed boundary method (GCIBM) for simulating turbulent flows in complex geometries is presented. A boundary condition is enforced through a ghost cell method. The reconstruction procedure allows systematic development of numerical schemes for treating the immersed boundary while preserving the overall second-order accuracy of the base solver. Both Dirichlet and Neumann boundary conditions can be treated. The current ghost cell treatment is both suitable for staggered and non-staggered Cartesian grids. The accuracy of the current method is validated using flow past a circular cylinder and large eddy simulation of turbulent flow over a wavy surface. Numerical results are compared with experimental data and boundary-fitted grid results. The method is further extended to an existing ocean model (MITGCM) to simulate geophysical flow over a three-dimensional bump. The method is easily implemented as evidenced by our use of several existing codes.

A Ghost-Cell Immersed Boundary Method for Flow in Complex Geometry

We describe the space–time finite element techniques we developed for computation of fluid–structure interaction (FSI) problems. Among these techniques are the deforming-spatial-domain/stabilized space–time (DSD/SST) formulation and its special version, and the mesh update methods, including the solid-extension mesh moving technique (SEMMT). Also among these techniques are the block-iterative, quasi-direct and direct coupling methods for the solution of the fully discretized, coupled fluid and structural mechanics equations. We present some test computations for the mesh moving techniques described. We also present numerical examples where the fluid is governed by the Navier– Stokes equations of incompressible flows and the structure is governed by the membrane and cable equations. Overall, we demonstrate that the techniques we have developed have increased the scope and accuracy of the methods used in computation of FSI problems. � 2005 Elsevier B.V. All rights reserved.

Space-time finite element techniques for computation of fluid-structure interactions

https://digital.library.unt.edu/ark:/67531/metadc933587/m2/1/high_res_d/978353.pdf

A reconstructed discontinuous Galerkin method for the compressible Navier-Stokes equations on arbitrary grids

The low thermal properties of liquids have led to investigations into additives of small size (less than 100 nm solid particles) to enhance their heat transfer properties and hydrodynamic flow. To summarise the experimental and numerical studies, this paper reviews these computational simulations and finds that most of them are in agreement with the results of experimental work. Many of the studies report enhancements in the heat transfer coefficient with an increase in the concentration of solid particles. Certain studies with a smaller particle size indicated an increase in the heat transfer enhancement when compared to values obtained with a larger size. Additionally, the effect of the shape of the flow area on the heat transfer enhancement has been explored by a number of studies. All of the studies showed a nominal increase in pressure drop. The significant applications in the engineering field explain why so many investigators have studied heat transfer with augmentation by a nanofluid in the heat exchanger. This article presents a review of the heat transfer applications of nanofluids to develop directions for future work. The high volume fraction of various nanofluids will be useful in car radiators to enhance the heat transfer numerically and experimentally. Correlation equations can expose relationships between the Nusselt number, the Reynolds number, the concentration and the diameter of the nanoparticles. On the other hand, more work is needed to compare the shapes (e.g., circular, elliptical and flat tube) that might enhance the heat transfer with a minimal pressure drop.

A review of forced convection heat transfer enhancement and hydrodynamic characteristics of a nanofluid

Mixed convection heat transfer in power law fluids over a moving conveyor along an inclined plate

Forced convection heat transfer from an unconfined circular cylinder in the steady cross-flow regime has been studied using a finite volume method (FVM) implemented on a Cartesian grid system in the range as 10 ≤ Re ≤ 45 and 0.7 ≤ Pr ≤ 400. The numerical results are used to develop simple correlations for Nusselt number as a function of the pertinent dimensionless variables. In addition to average Nusselt number, the effects of Re, Pr and thermal boundary conditions on the temperature field near the cylinder and on the local Nusselt number distributions have also been presented to provide further physical insights into the nature of the flow. The rate of heat transfer increases with an increase in the Reynolds and/or Prandtl numbers. The uniform heat flux condition always shows higher value of heat transfer coefficient than the constant wall temperature at the surface of the cylinder for the same Reynolds and Prandtl numbers. The maximum difference between the two values is around 15–20%.

A numerical study of the steady forced convection heat transfer from an unconfined circular cylinder

Steady forced convection heat transfer from a heated circular cylinder to power-law fluids

The momentum equations describing the steady cross-flow of power law fluids past an unconfined circular cylinder have been solved numerically using a semi-implicit finite volume method The numerical results highlighting the roles of Reynolds number and power law index on the global and detailed flow characteristics have been presented over wide ranges of conditions as 5 ≤ Re ≤ 40 and 06 ≤ n ≤ 2 The shear-thinning behaviour (n 1) show the opposite behaviour Furthermore, while the wake size shows non-monotonous variation with the power law index, but it does not seem to influence the values of drag coefficient The stagnation pressure coefficient and drag coefficient also show a complex dependence on the power law index and Reynolds number In addition, the pressure coefficient, vorticity and viscosity distributions on the surface of the cylinder have also been presented to gain further physical insights into the detailed flow kinematics

Ram P. Bharti

Papers

A numerical study of the steady forced convection heat transfer from an unconfined circular cylinder

Steady forced convection heat transfer from a heated circular cylinder to power-law fluids

Steady Flow of Power Law Fluids across a Circular Cylinder

Effect of power-law index on critical parameters for power-law flow across an unconfined circular cylinder

Forced convection heat transfer from an elliptical cylinder to power-law fluids