Bulletin of the American Physical Society
67th Annual Meeting of the APS Division of Fluid Dynamics
Volume 59, Number 20
Sunday–Tuesday, November 23–25, 2014; San Francisco, California
Session R1: General Fluid Dynamics IV |
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Chair: Ralph Metcalfe, University of Houston Room: 3000 |
Tuesday, November 25, 2014 1:05PM - 1:18PM |
R1.00001: Size-Dependent Couple Stress Fluid Mechanics: The Influence of Boundary Conditions Arezoo Hajesfandiari, Ali Hadjesfandiari, Gary Dargush In size-dependent couple stress fluid mechanics, which involves a length parameter $l$, the corresponding modified Navier-Stokes equations are $\rho \frac{D{\rm {\bf v}}}{Dt}=-\nabla p+\mu \;\nabla^{2}{\rm {\bf v}}-\mu l^{2}\;\nabla^{2}\nabla^{2}{\rm {\bf v}}$. The term involving $l$ is of fourth order, which then requires the prescription of additional boundary conditions compared to the classical case. Therefore, the boundary conditions in the size-dependent theory must include specification of either the tangential component of rotations ${\rm {\bf \omega }}$ on the boundary or the tangential moment-tractions ${\rm {\bf m}}^{\left( n \right)}$. Here we concentrate on two-dimensional flows and explore the consequences of prescribing different boundary conditions in size-dependent couple-stresses fluid mechanics by using computational fluid dynamics. We investigate the characteristics of flow for the cavity problem based upon the equation above and the Boussinesq approximation for the Rayleigh-Benard problem. This provides us with interesting, unexpected results for various boundary conditions, when accounting for couple-stresses. These in turn might explain different mechanisms for energy dissipation, as well as for chaotic behaviors of fluid flow. [Preview Abstract] |
Tuesday, November 25, 2014 1:18PM - 1:31PM |
R1.00002: Geometric and Dynamic Skewness in Passive Scalar Transport Richard McLaughlin, Manuchehr Aminian, Francesca Bernardi, Roberto Camassa The evolution of a passive scalar in laminar shear flow is revisited in channel, pipe, and box geometries. Exact, explicit closed form, single sum formulae for the evolution of the skewness of a passive scalar along span-wise slices are derived and studied analytically in the case of channel flow. The largest skewness in time is interpreted using a geometric quantity. Surprisingly, the geometric quantity is seen to be absent in the smooth pipe geometries, but present in the box geometry, providing insight into the role of the wall mode versus center mode in assigning the sign to the instantaneous averaged skewness. [Preview Abstract] |
Tuesday, November 25, 2014 1:31PM - 1:44PM |
R1.00003: Relativistic fluids: fundamentals and recent developments A. Sandoval-Villalbazo, A.L. Garc\'Ia-Perciante Relativistic thermodynamics and kinetic theory have been subjects of intense research and debate recently. The topic has gained attention primarily due to its application in both astrophysical and experimental scenarios. In this talk I will review some of the challenges theorists have faced in search of a successful formalism capable of describing these systems and the alternatives proposed in order to avoid the well known instabilities and causality problems present in the first works on the subject published more than fifty years ago. Among these proposals I will focus on the first order in the gradients version of relativistic kinetic theory in order to describe special relativistic single component fluids in the presence of external forces. The main results obtained following this path will be shown including the relativistic expressions for dissipative fluxes and entropy production. Some consequences of relativistic modifications in the hydrodynamic equations will also be discussed. [Preview Abstract] |
Tuesday, November 25, 2014 1:44PM - 1:57PM |
R1.00004: Shape optimization for continuum with H1 gradient method Takashi Nakazawa In this presentation, shape optimization of continuum is operated in the domain of interest which Navier-Stokes equation governs. And more, DNS is operated for the domain before and after shape optimization. By comparing the results of DNS in the before and after shape optimized domains, it is discussed that which domain is better. [Preview Abstract] |
Tuesday, November 25, 2014 1:57PM - 2:10PM |
R1.00005: Numerical simulation of flow in a horizontal channel with multiple cross-flow inlets Pranab N. Jha, Chuck Smith, Ralph W. Metcalfe Flow in a horizontal channel with multiple cross-flow inlets was studied numerically. Based on Reynolds and Mach number analysis of data obtained from a horizontal natural gas well having 31 completion stages, measured at two different times in the production cycle, it was determined that an incompressible flow model may be applied to study a large fraction of the wellbore. Using five cross-flow inlets, the existence of three basic flow regimes - trickle flow, partially blocked flow and fully blocked flow - were identified with respect to the blocking of upstream inlets by the downstream ones. The existence of these flow regimes is consistent with field data. A lumped-parameter model for pressure drop was used to simulate large axial distances between two inlets. A pressure boundary condition was employed at each inlet to simulate a linearly depleting reservoir. This was used to study the dynamic interaction between the inlets in the channel. The characteristic time scales related to the transient depletion were identified and analyzed. The transition of flow regimes is consistent with the trends observed from field data and gives an insight into the behavior of horizontal wells. [Preview Abstract] |
Tuesday, November 25, 2014 2:10PM - 2:23PM |
R1.00006: Vibration-Induced Rectified Motion of a Piston in a Liquid-Filled Cylinder with Bellows to Mimic Gas Regions J.R. Torczynski, L.A. Romero, J.R. Clausen, T.J. O'Hern The motion of a piston within a cylinder is investigated. A spring suspends the piston against gravity. The cylinder is filled with a viscous liquid and has compressible bellows at the top and bottom to mimic gas regions. A fixed post with protrusions extends into a hole through the piston with opposing protrusions. The length of the gap formed by the protrusions depends on the piston's vertical position. The outer gap between the piston and the cylinder is extremely small. Hence, as the piston moves, the displaced liquid passes through the variable-length gap, and the liquid force on the piston depends on its position. When this system is subjected to vertical vibrations, this dependence can produce a nonzero net force. With bellows, this net force can become large enough for the piston to compress the spring. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Tuesday, November 25, 2014 2:23PM - 2:36PM |
R1.00007: Simulating Rectified Motion of a Piston in a Housing Subjected to Vibrational Acceleration Jonthan Clausen, John Torczynski, Louis Romero, Timothy O'Hern We employ ALE finite element simulations to investigate the behavior of a piston in a housing subjected to vertical vibrations. The housing is filled with a viscous liquid to damp the piston motion and has bellows at both ends to represent air bubbles present in real systems. The piston has a roughly cylindrical hole along its axis, and a post attached to the housing penetrates partway into this hole. Protrusions from the hole and the post form a gap with a length that varies as the piston moves and forces liquid through this gap. Under certain conditions, nonlinearities in the system can drive the piston to move downward and compress the spring that holds it up against gravity. This behavior is investigated using ALE finite element simulations, and these results are compared with theoretical predictions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Tuesday, November 25, 2014 2:36PM - 2:49PM |
R1.00008: Optimal Dynamics of Intermittent Water Supply Anna Lieb, Jon Wilkening, Chris Rycroft In many urban areas of the developing world, piped water is supplied only intermittently, as valves direct water to different parts of the water distribution system at different times. The flow is transient, and may transition between free-surface and pressurized, resulting in complex dynamical features with important consequences for water suppliers and users. These consequences include degradation of distribution system components, compromised water quality, and inequitable water availability. The goal of this work is to model the important dynamics and identify operating conditions that mitigate certain negative effects of intermittent water supply. Specifically, we will look at valve parameters occurring as boundary conditions in a network model of transient, transition flow through closed pipes. Optimization will be used to find boundary values to minimize pressure gradients and ensure equitable water availability. [Preview Abstract] |
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