Bulletin of the American Physical Society
69th Annual Meeting of the APS Division of Fluid Dynamics
Volume 61, Number 20
Sunday–Tuesday, November 20–22, 2016; Portland, Oregon
Session A29: CFD: Applications I |
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Chair: Sourabh Apte, Oregon State University Room: F150 |
Sunday, November 20, 2016 8:00AM - 8:13AM |
A29.00001: Numerical study on the interaction between supercavitation and turbulence Han Liu, Zuoli Xiao, Lian Shen Supercavitation uses a bubble of~gas~inside a~liquid~large enough to encompass an object travelling through the liquid so that the skin friction on the object can be greatly reduced and high speed can be obtained. In this study, computational fluid dynamics is used to investigate the interaction between supercavitation and turbulence. The study builds on an in-house simulation code that uses the coupled level set and volume of fluid method to accurately capture the interface between the water and gas phases. A ventilated disk cavitator is used for the bubble generation, and it is modelled by a sharp interface immersed boundary method. Turbulence in the incoming flow is generated by a grid of small spheres upstream. Based on the simulation data, the influence of turbulence on the supercavitation and the underlying mechanisms are analyzed. [Preview Abstract] |
Sunday, November 20, 2016 8:13AM - 8:26AM |
A29.00002: Sprocket- Chain Simulation: Modelling and Simulation of a Multi Physics problem by sequentially coupling MotionSolve and nanoFluidX Aditya Jayanthi, Christopher Coker In the last decade, CFD simulations have transitioned from the stage where they are used to validate the final designs to the main stream development of products driven by the simulation. However, there are still niche areas of applications liking oiling simulations, where the traditional CFD simulation times are probative to use them in product development and have to rely on experimental methods, which are expensive. In this paper a unique example of Sprocket- Chain simulation will be presented using nanoFluidx a commercial SPH code developed by FluiDyna GmbH and Altair Engineering. The grid less nature of the of SPH method has inherent advantages in the areas of application with complex geometry which pose severe challenge to classical finite volume CFD methods due to complex moving geometries, moving meshes and high resolution requirements leading to long simulation times. The simulations times using nanoFluidx can be reduced from weeks to days allowing the flexibility to run more simulation and can be in used in main stream product development. The example problem under consideration is a classical Multiphysics problem and a sequentially coupled solution of Motion Solve and nanoFluidX will be presented. [Preview Abstract] |
Sunday, November 20, 2016 8:26AM - 8:39AM |
A29.00003: Multi-fidelity modelling for flow over a cylinder Prerna Patil, Hessam Babaee, George Karniadakis We tackle the classical problem of predicting the relation between C$_{\mathrm{L}}$, C$_{\mathrm{D}}$ and C$_{\mathrm{P}}$ vs Reynolds number for flow over cylinder using the multi-fidelity framework. The stochastic response surface is obtained by implementing the auto-regressive stochastic modelling (Kennedy and O'Hagan, 2000) and Gaussian process regression to combine data from variable levels of fidelity. In particular, we predict the lift, drag and pressure coefficients where codes with multiple levels of fidelity are available. We correlate data at each of these levels and build the surrogate model using multi-level recursive co-kriging. The deficient physics of the low-fidelity model is explored by examining the cross-correlation between the low-fidelity and high-fidelity models. The proposed framework ultimately intends to meld computational accuracy of the expensive high fidelity with the computational cost of the inexpensive low-fidelity. [Preview Abstract] |
Sunday, November 20, 2016 8:39AM - 8:52AM |
A29.00004: Electrohydrodynamic deformation of capsules in electric field Sudip Das, Rochish Thaokar Micron size capsules are abundant in natural, technological and biological processes but they still require extensive investigation for better understanding of their mechanical behavior. A spherical capusle containing a Newtonian fluid bounded by a viscoelastic membrane and immersed in another Newtonian fluid, and subject to electric field is considered. Discontinuity of electrical properties such as conductivity and permittivity leads to a net Maxwell stress at the capsule interface. In response the capsule undergoes elastic deformation, leading to strain fields and elastic stresses that can balance the applied forces. We investigate this problem with fully resolved hydrodynamics in the Stokes flow limit and electrostatics using the capacitance model. Effect of AC, DC and pulsed DC fields is investigated. Our results show that membrane electrical properties have a huge impact on the equilibrium deformation as well as on the break up of capsules. Our results match with the literature results in the limit of high conductance of the membrane. Analytical theory is employed using spherical harmonics and numerical investigations are conducted using the Boundary integral method. [Preview Abstract] |
Sunday, November 20, 2016 8:52AM - 9:05AM |
A29.00005: ABSTRACT WITHDRAWN |
Sunday, November 20, 2016 9:05AM - 9:18AM |
A29.00006: Convective heat transfer by oscillating flow in an enclosure with non-uniform spatial bottom wall temperature profile saeid raheimpour angeneh, murat kadri aktas Effects of the acoustic streaming motion on convective heat transfer in a rectangular shallow enclosure with sinusoidal spatial bottom wall temperature distribution are investigated numerically. Acoustic excitation is generated by the periodic vibration of left wall. The top wall of the enclosure is isothermal while the side walls are adiabatic. A FORTRAN code is developed to predict the oscillatory and mean flow fields by considering the compressible form of the Navier -Stokes equation and solved by flux-corrected transport algorithm. In order to validate the results of the simulations, a case with an unheated bottom wall is considered and compared with the existing literature. Applying the sinusoidal temperature profile to the bottom wall provides axial and transverse temperature gradients. In return these gradients strongly affect the flow pattern in the enclosure. Heat transfer depends on the flow structure considerably. This is the first time that the effect of nonzero mean vibrational flow on thermal convection from a surface with sinusoidal temperature profile investigated. Results of this study may lead up to design of new heat removal applications. [Preview Abstract] |
Sunday, November 20, 2016 9:18AM - 9:31AM |
A29.00007: Computing the numerical solution to functional differential equations: some recent progresses towards E. Hopf's 1952 dream Daniele Venturi The fundamental importance of functional differential equations has been recognized in many areas of mathematical physics, such as fluid dynamics, quantum field theory and statistical physics. For example, in the context of fluid dynamics, the Hopf characteristic functional equation was deemed by Monin and Yaglom to be ``the most compact formulation of the turbulence problem'', which is the problem of determining the statistical properties of the velocity and pressure fields of Navier-Stokes equations given statistical information on the initial state. However, no effective numerical method has yet been developed to compute the solution to functional differential equations. In this talk I will provide a new perspective on this general problem, and discuss recent progresses in approximation theory for nonlinear functionals and functional equations. The proposed methods will be demonstrated through various examples. [Preview Abstract] |
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