Bulletin of the American Physical Society
72nd Annual Meeting of the APS Division of Fluid Dynamics
Volume 64, Number 13
Saturday–Tuesday, November 23–26, 2019; Seattle, Washington
Session H07: Focus Session: Smoothed Particle Hydrodynamics for Simulating Fluid Flow |
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Chair: Angelo Tafuni Room: 211 |
Monday, November 25, 2019 8:00AM - 8:13AM |
H07.00001: On particle distribution in High-Order Smoothed Particle Hydrodynamics schemes Invited Speaker: Renato Vacondio Smoothed particle hydrodynamics (SPH) numerical schemes are becoming very popular in CFD due to their Lagrangian and meshless nature. Nevertheless, many arising numerical issues still remain to be investigated. One of the major drawback of such meshless schemes is the low order convergence rate due to particle spatial anisotropy. To overcome this, considerable work has been done towards introducing kernel corrections. Nevertheless, these might lead to instabilities and break the conservation properties of the numerical scheme. Recently, it was demonstrated that schemes such as “diffusion-based particle shifting” are able to improve the accuracy of the approximations however, they do not conserve linear and angular momentum. In the present work, an arbitrary Lagrangian-Eulerian scheme (ALE-SPH) has been developed where the transport velocity is computed by means of an iterative particle shifting scheme which ensures a near isotropic particle distribution spatially. Moreover, a new class of kernels have been adopted that can guarantee an arbitrary order of convergence (at the continuous level of spatial interpolation). In this way, we have been able to attain the theoretical order of convergence of the adopted kernel (for example 4th or 6th order) preserving the conservation properties. [Preview Abstract] |
Monday, November 25, 2019 8:13AM - 8:26AM |
H07.00002: Modeling Astrophysical Transients with Smooth Particle Hydrodynamics Chris Fryer Mesh free methods, and smooth particle hydrodynamics in particular, have been used extensively in modeling astrophysical transients. The ability of SPH to conserve angular momentum, easily include detailed microphysics, and to resolve the mass over large distance scales makes it an ideal method for many problems. I will present an overview of the wide variety of astrophysical transients modeled with smooth particle hydrodynamics, including supernovae, gamma-ray bursts and merging neutron stars. I will focus on the specific strengths and current issues using these methods to model these problems. [Preview Abstract] |
Monday, November 25, 2019 8:26AM - 8:39AM |
H07.00003: Incompressible SPH and New Developments Steven Lind SPH shows considerable promise for modelling a range of challenging fluid phenomena, especially those involving highly deforming free-surface flows or interfaces with potential topology change. SPH is often applied in weakly compressible form, but incompressible SPH is a newer alterative gaining popularity given its ability to predict accurate pressure fields without the use of empirical equations of state, artificial sound speeds, or excessive numerical diffusion. This talk will provide an overview of recent developments for the incompressible SPH approach, including examples of its application in quite diverse areas of fluid mechanics. New methodologies for achieving stability and very high accuracy will also be discussed. [Preview Abstract] |
Monday, November 25, 2019 8:39AM - 8:52AM |
H07.00004: A spatially adaptive high-order meshless method for fluid-structure interactions Wenxiao Pan, Wei Hu, Nathaniel Trask We present a scheme implementing an a posteriori refinement strategy in the context of a high-order meshless method for problems involving point singularities and fluid-solid interfaces. The generalized moving least squares (GMLS) discretization used in this work has been previously demonstrated to provide high-order compatible discretization of the Stokes and Darcy problems, offering a high-fidelity simulation tool for problems with moving boundaries. The meshless nature of the discretization is particularly attractive for adaptive $h$-refinement, especially when resolving the near-field aspects of variables and point singularities governing lubrication effects in fluid-structure interactions. We demonstrate that the resulting spatially adaptive GMLS method is able to achieve optimal convergence in the presence of singularities for both the div-grad and Stokes problems. Further, we present a series of simulations for flows of colloid suspensions, in which the refinement strategy efficiently achieved highly accurate solutions, particularly for colloids with complex geometries. [Preview Abstract] |
Monday, November 25, 2019 8:52AM - 9:05AM |
H07.00005: Projection Particle Methods - Latest Advances and Future Perspectives Abbas Khayyer This talk comprises of a review on the latest achievements made in the context of projection particle methods. Projection particle methods, including Incompressible Smoothed Particle Hydrodynamics (ISPH) and Moving Particle Semi-implicit (MPS), are founded on Helmholtz-Leray decomposition and its corresponding Chorin's projection method. In this talk this important mathematical concept and related mathematical conditions will be reviewed and its application for ISPH and MPS will be concisely described. Followed by providing the mathematical background, the ISPH and MPS numerical methods will be briefly introduced. The latest achievements corresponding to stability, accuracy and energy conservation enhancements as well as advancements related to simulations of multi-phase flows and hydroelastic fluid-structure interactions will be discussed. In specific, more attention will be dedicated to hydroelastic fluid-structure interactions in the context of projection particle methods, introducing methods for interactions of incompressible fluid flows with elastic structures in both Newtonian and Hamiltonian frameworks. Finally, the future perspectives for further enhancements of applicability and reliability of particle methods will be highlighted. [Preview Abstract] |
Monday, November 25, 2019 9:05AM - 9:18AM |
H07.00006: Multiscale SPH model for multiphase flow Alexandre Tartakovsky, Amanda Howard We present nonlocal multiscale partial differential equations for multiphase flow and their smoothed particle hydrodynamics (SPH) discretization. We demonstrate that this model is able to describe multiphase flow at scales ranging from micro (nano) to macro scales and predicts curvature dependence of the surface tension. The nonlocal model is obtained in the form of an integral of a molecular-force-like function added into the momentum conservation equation. Our SPH simulations of multiphase flow in porous materials and droplet and film flow on rough surfaces further reveal multiscale features of the proposed model. [Preview Abstract] |
(Author Not Attending)
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H07.00007: Anisotropic dispersion with a consistent smoothed particle hydrodynamics scheme Jaime Klapp, Carlos E Alvarado-Rodriguez, Leonardo Sigalotti, Ayax H Torres-Victoria A consistent smoothed particle hydrodynamics (SPH) approach is used to simulate the anisotropic dispersion of a solute in porous media. Consistency demands using large numbers of neighbors with increasing resolution. The method is tested against the anisotropic dispersion of a Gaussian contaminant plume. With irregularly distributed particles, the solution for isotropic dispersion converges to second-order accuracy when at sufficiently high resolution a large number of neighbors is used within the kernel support. For low to moderate anisotropy, the convergence rates are close to second-order, while for large anisotropic dispersion the solutions converge to better than first-order. For randomly distributed particles, the solutions are also better than first order independently of the degree of anisotropy. When negative concentrations arise, they are several orders of smaller magnitude than those encountered with standard SPH and comparable to those obtained with the MWSPH scheme of Avesani et al. The method is also insensitive to particle disorder and achieves an overall accuracy comparable to the MWSPH method using a much simpler approach. [Preview Abstract] |
Monday, November 25, 2019 9:31AM - 9:44AM |
H07.00008: Hydrodynamic Study of an Extraterrestrial Ship Design with SPH Angelantonio Tafuni, Jason W. Hartwig, Steven R. Oleson, Ralph D. Lorenz NASA is considering an ad-hoc ship design to send to Titan's seas as an alternative to the model submarine proposed in recent studies. The purpose of the mission would be to carry out scientific investigations autonomously above and under the surface of Titan's seas, the latter to be conducted via deployable dropsondes stored within the ship's interior. In this talk, results from a thoroughly conducted computational analysis will be presented, with a cost-effective and efficient approach to calculate the ship's resistance based on its design and surroundings, and to determine power requirements. Smoothed particle hydrodynamics (SPH) is employed via the state-of-the-art code DualSPHyiscs. Recently developed open boundary conditions are implemented to limit the size of the computational domain, allowing the use of finer levels of resolution to resolve the physics accurately. The main objectives of the present work are 1) to analyze and understand the effect of non-Earth-like navigation conditions, such as lower gravity environment and sea composition; 2) to investigate the effect of flow parameters such as ship's speed and sinkage on the total hydrodynamic resistance, and 3) to estimate the Effective Horsepower (EHP) and total propulsion power required. [Preview Abstract] |
Monday, November 25, 2019 9:44AM - 9:57AM |
H07.00009: A comparison of three SPH methods for the solution of the Fluid-Solid Interaction problem Milad Rakhsha, Lijing Yang, Dan Negrut We report results and lessons learned from a study in which three Smoothed Particle Hydrodynamics (SPH)-methods were used for the solution of several fluid-solid Interaction problems. The first SPH approach considered is widely used in the community and it relies on an equation of state to weakly enforce compressibility (called WCSPH, from Weakly Compressible SPH). The second SPH approach uses an implicit solution in which the incompressibility is enforced by a pressure distribution computed via a Poisson equation (called ISPH, from Implicit SPH). Lastly, a constraint-based method is considered that enforces incompressibility by imposing the constant density condition via a kinematic holonomic constraint on the motion of the SPH markers (called KCSPH, from Kinematically Constrained SPH). WCSPH, ISPH and KCSPH are compared in conjunction with five tests: an incompressibility benchmark test, Poiseuille flow, flow around cylinder, dam break, and fluid sloshing. The interest is in comparing solution attributes such as accuracy, robustness, efficiency, and ease of use and implementation. Ultimately, this effort provided a mechanism to probe the agency of the SPH method. [Preview Abstract] |
Monday, November 25, 2019 9:57AM - 10:10AM |
H07.00010: GPUSPH modeling of waves and currents in the nearshore Robert Dalrymple, Morteza Derakhti GPUSPH (www.gpusph.org) is an open-source Smoothed Particle Hydrodynamics code that has been developed since 2009 for application to free surface flows using the massively parallel architecture of the graphics processing unit (GPU) for computational speed Here we show examples of water waves breaking within the surf zone and wave-induced flows in 3D. The basic example consists of two incident synchronous wave trains with different directions. As shown by Dalrymple (JGR, 1975), synchronous wave trains lead to the formation of nodal and anti-nodal lines in the water surface by superposition. This leads to the formation of circulation cells in the nearshore with rip currents flowing offshore on the nodal lines. However, this is only true for small amplitude waves as nonlinear amplitude diffraction leads to waves crossing the linear nodal lines. This leads to isolated wave crests (Wei et al. ,2017) and an increase in the number of waves in the surf zone. This nonlinear effect leads to additional circulation cells within the surf zone. We also examine the magnitude of each term in the wave-averaged equation of motion spatially. [Preview Abstract] |
Monday, November 25, 2019 10:10AM - 10:23AM |
H07.00011: Granular dynamics vs. fluid dynamics: similarities and differences Milad Rakhsha, Conlain Kelly, Nicholas Olsen, Dan Negrut In understanding the dynamics of granular systems, discrete modeling of granular flows requires tracking particles whose motion is by and large shaped by frictional contact forces. Such an approach is challenged when the particle size is small, e.g., sub millimeter, and/or when the number of particles is large, e.g., one billion particles and beyond. In these cases, one can contemplate switching to continuum models for granular dynamics. Inspired by the fluid-like behavior of granular material, in this contribution we report on an approach in which granular material dynamics is approximated via a fluid flow. The results reported draw on computer simulations using the Discrete Element Method (DEM) to solve the Newton-Euler equations of motion. For the fluid flow, we employ the Smoothed Particle Hydrodynamics (SPH) to solve the Navier-Stokes equations. Similarities and differences between the discrete, fully resolved model and the continuum granular material model are reported drawing on a set of three numerical experiments: compressibility test, the classical dam break problem, and the dam break simulation with an obstacle. [Preview Abstract] |
Monday, November 25, 2019 10:23AM - 10:36AM |
H07.00012: Numerical simulation of the fluid-structure interaction in an airship through the SPH methodology. Oscar I. Rocha-Lopez, Ruben Avila, Alejandro Garcia Airships currently maintained an interest in the scientific field due to their specific flight properties and advantages. However, one of the problems that arise is the way to maintain stability during the flight of these vehicles. In this research, using the free code DualSPHysics (SPH method), the fluid-structure interaction of the YEZ-2A airship (USA Navy, 1989) is analyzed. The Lagrangian methodology is used to study the stability of the Rolling, Pitching and Yawing moments, and the drag and lift average aerodynamic coefficients. It is assumed that the airship is flying in a low Reynolds number regime in a quasi-compressible medium (air). The numerical results are compared with previous studies, both experimental and numerical simulations using the traditional Eulerian-mesh based methods. [Preview Abstract] |
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