Semi‐analytical Solid Boundary Conditions for Free Surface Flows

2020 ◽  
Vol 39 (7) ◽  
pp. 131-141
Author(s):  
Yue Chang ◽  
Shusen Liu ◽  
Xiaowei He ◽  
Sheng Li ◽  
Guoping Wang
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Free Surface Flows ◽  
Solid Boundary ◽  
Surface Flows

Evaluation of the Solid Boundary Treatment Methods in SPH

2018 ◽  
Vol 01 (02) ◽  
pp. 1840002 ◽  
Author(s):  
Shilong Liu ◽  
Ioan Nistor ◽  
Majid Mohammadian
Keyword(s):  
Free Surface ◽  
Free Water ◽  
Treatment Method ◽  
Free Surface Flows ◽  
Solid Boundary ◽  
Surface Flows ◽  
Boundary Treatment ◽  
Particle Hydrodynamics ◽  
Source Models ◽  
Definition Of

The smoothed particle hydrodynamics (SPH) method has been proved as a powerful algorithm for fluid mechanics, especially in the simulation of free surface flows with high speeds or drastic impacts. The solid boundary treatment method is important for the accuracy and stability of the numerical results, as the support domain of fluid particles is truncated near the vicinity of the boundary. This paper presents two commonly used methods for simulating a solid boundary in SPH simulations. Emphasis is placed on the description of the methods, definition of the boundary particles’ parameters, and discussion of their advantages and shortcomings. The classical dam break simulation is conducted using self-developed code and open source models such as DualSPHysics and PySPH in order to investigate the effects of the boundary methods. The results show that methods based on dynamic boundary particles can simulate the free water surface well with a good agreement with experimental results. The conclusions can also be used in research for boundary implementation methods for practical ocean and coastal engineering problems with free surface flows.

Hybrid SW-NS SPH models using open boundary conditions for simulation of free-surface flows

2020 ◽  
Vol 196 ◽  
pp. 106845 ◽  
Author(s):  
Xingye Ni ◽  
Weibing Feng ◽  
Shichang Huang ◽  
Xin Zhao ◽  
Xinwen Li
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Free Surface Flows ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Surface Flows

Analysis of Variable Porosity, Thermal Dispersion, and Local Thermal Nonequilibrium on Free Surface Flows Through Porous Media

2004 ◽  
Vol 126 (3) ◽  
pp. 389-399 ◽  
Author(s):  
Bader Alazmi ◽  
Kambiz Vafai
Keyword(s):  
Porous Media ◽  
Free Surface ◽  
Free Surface Flows ◽  
Solid Boundary ◽  
Thermal Dispersion ◽  
Thermal Nonequilibrium ◽  
Surface Flows ◽  
Variable Porosity ◽  
Flows Through Porous Media ◽  
Local Thermal Nonequilibrium

Characteristics of momentum and energy transport for free surface flows through porous media are explored in this study. Effects of variable porosity and an impermeable boundary on the free surface front are analyzed. In addition, effects of thermal dispersion and local thermal nonequilibrium (LTNE) are also analyzed. Pertinent parameters such as porosity, Darcy number, inertia parameter, Reynolds number, particle diameter, and solid-to-fluid conductivity ratio are used to investigate the significance of the above mentioned effects. Results show that considering the effect of variable porosity is significant only in the neighborhood of the solid boundary. The range of parameters which enhance the dispersion and LTNE effects are prescribed. Finally, it is shown that adding the effect of thermal dispersion to LTNE increases the sensitivity of LTNE between the two phases.

A Simple Verification Test for Nonlinear Flow Calculations Around a Ship Hull Steadily Advancing in Calm Water

2012 ◽  
Vol 56 (03) ◽  
pp. 162-169
Author(s):  
Francis Noblesse ◽  
Lijue Wang ◽  
Chi Yang
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Free Surface Flows ◽  
Wave Profile ◽  
Surface Flows ◽  
Ship Hulls ◽  
Euler Flow ◽  
Numerical Predictions ◽  
Calm Water ◽  
Analytical Relations

Simple analytical relations that can readily be applied to verify a critical aspect of numerical predictions of fully nonlinear free-surface flows around ship hulls steadily advancing in calm water are given. The relations do not involve the flow field equations; that is, they are only based on the boundary conditions at the ship hull surface and at the free surface. These boundary conditions have a predominant influence on free-surface flows around advancing ship hulls. The analytical relations are exact for inviscid flows, and can be applied to numerical methods that solve either the Laplace equation (potential-flow methods) or the Euler flow equations (CFD Euler-flow methods). They provide a simple test to verify if numerical predictions given by nonlinear potential-flow or Euler-flow methods correctly satisfy the hull-surface and free-surface boundary conditions along the contact curve between the hull surface and the free surface. The relations might also be used to verify CFD methods that solve the RANS equations if they are applied at the edge of the viscous boundary layer. The analytical test can identify an inconsistency, which might point to a "method issue" related to a feature of a numerical method (e.g., a numerical-differentiation scheme) or an "implementation issue" in the implementation of the method (e.g., a poor discretization). For purposes of illustration, the test is applied to predictions of flows around the Wigley parabolic hull given by two CFD methods that solve the Euler equations with fully nonlinear boundary conditions at the free surface. This illustrative example demonstrates that the test can indeed be useful to identify numerical inaccuracies. The analytical relations can also be used to determine experimental values of the flow velocity at a ship wave profile that correspond to measurements of the wave profile.

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