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

Part I. The Surface Vorticity Boundary Integral Method of Fluid Flow Analysis: 1. The basis of surface singularity modelling 2. Lifting bodies, two-dimensional aerofoils and cascades 3. Mixed-flow and radial cascades 4. Bodies of revolution, ducts and annuli 5. Ducted propellers and fans 6. Three-dimensional and meridional flows in turbo-machines 7. Free vorticity shear layers and inverse methods Part II. Vortex Dynamics and Vortex Cloud Analysis: 8. Vortex dynamics in inviscid flows 9. Simulation of viscous diffusion in discrete vortex modelling 10. Vortex cloud modelling by the boundary integral method 11. Further development and applications of vortex cloud modelling to lifting bodies and cascades 12. Use of grid systems in vortex dynamics and meridional flows Appendix.

Vortex Element Methods for Fluid Dynamic Analysis of Engineering Systems: Vortex cloud modelling by the boundary integral method

Particle methods in ocean and coastal engineering

Entirely Lagrangian meshfree computational methods for hydroelastic fluid-structure interactions in ocean engineering—Reliability, adaptivity and generality

Large eddy simulation and experimental investigation on the cavity dynamics and vortex evolution for oblique water entry of a cylinder

Numerical simulations of sloshing flows with an elastic baffle using a SPH-SPIM coupled method

In this work, a developed Shear Stress Transport (SST) model has been used for numerically simulating the problem of turbulent round jet impingement heat transfer. Based on the cross-diffusion correction activated in the logarithmic and wake parts of a region by using a blending function in the destruction term of turbulent kinetic energy k, the developed SST model is capable of recovering the effect of the pressure gradient ignored by the standard SST model. Also, the Kato-Launder model is added in the production term of k to consider the stagnating flows. The developed model has been investigated for turbulent round jets with the nozzle-plate spacing of 2, 4, and 6. The model is verified by comparing with the measurements and the results of the standard SST model, the SST with low-Re model, the Launder and Sharma model with the Yap model, the k-ω model, and the Reynolds-averaged Navier-Stokes/large eddy simulation model. Comparing with other referred methods, the developed model obtains accurate prediction in terms of velocity and pressure. As for heat transfer, it also possesses appropriate performance. Moreover, the developed model is sensitive to the pressure gradient, which helps the model be capable of reproducing accurate flow structures. By using the present model, it has been found that the velocity profiles are dominated by the turbulent kinetic energy away from walls. Meanwhile, the results show that the inner peak of heat transfer is connected with the radial pressure gradient at the stagnation point.

Analysis of the performance of a new developed shear stress transport model in a turbulent impinging jet flow

Numerical estimation of ship resistance in broken ice and investigation on the effect of floe geometry

To solve the problem of inaccurate boundary identification and to eliminate the spurious pressure oscillation in the previously developed immersed smoothed point interpolation method (IS-PIM), a new sharp-interface IS-PIM combining mass conservation algorithm, called Sharp-ISPIM-Mass, is proposed in this work. Based on the so called sharp-interface method, the technique of quadratic local velocity reconstruction has been developed by combining with the mass conservation algorithm, which enables the present method improve the accuracy of the velocity field and satisfy the mass conservation condition near the boundary field. So the proposed method would not encounter the problem of spurious mass flux. In addition, a new form of FSI force evaluation considering pressure and viscous force to perform a whole function from the fluid domain to fictitious fluid domain is introduced, which makes the present method obtain more accurate results of FSI force than the original one. Through the numerical studies of a number of benchmark examples, the performance of the Sharp-ISPIM-Mass has been examined and illustrated.

Zhe Sun

Papers

Large eddy simulation and experimental investigation on the cavity dynamics and vortex evolution for oblique water entry of a cylinder

Numerical simulations of sloshing flows with an elastic baffle using a SPH-SPIM coupled method

Analysis of the performance of a new developed shear stress transport model in a turbulent impinging jet flow

Numerical estimation of ship resistance in broken ice and investigation on the effect of floe geometry

A sharp-interface immersed smoothed point interpolation method with improved mass conservation for fluid-structure interaction problems