A New Computational Procedure to Predict Transient Hydroplaning Performance of a Tire

2001 ◽  
Vol 29 (1) ◽  
pp. 2-22 ◽  
Author(s):  
T. Okano ◽  
M. Koishi
Keyword(s):  
Complex Geometry ◽  
Fluid Flows ◽  
Computational Procedure ◽  
Vehicle Body ◽  
Fluid Viscosity ◽  
Safe Driving ◽  
Transient Phenomena ◽  
Vehicle Velocity ◽  
Fixed Reference ◽  
Volume Method

Abstract “Hydroplaning characteristics” is one of the key functions for safe driving on wet roads. Since hydroplaning depends on vehicle velocity as well as the tire construction and tread pattern, a predictive simulation tool, which reflects all these effects, is required for effective and precise tire development. A numerical analysis procedure predicting the onset of hydroplaning of a tire, including the effect of vehicle velocity, is proposed in this paper. A commercial explicit-type FEM (finite element method)/FVM (finite volume method) package is used to solve the coupled problems of tire deformation and flow of the surrounding fluid. Tire deformations and fluid flows are solved, using FEM and FVM, respectively. To simulate transient phenomena effectively, vehicle-body-fixed reference-frame is used in the analysis. The proposed analysis can accommodate 1) complex geometry of the tread pattern and 2) rotational effect of tires, which are both important functions of hydroplaning simulation, and also 3) velocity dependency. In the present study, water is assumed to be compressible and also a laminar flow, indeed the fluid viscosity, is not included. To verify the effectiveness of the method, predicted hydroplaning velocities for four different simplified tread patterns are compared with experimental results measured at the proving ground. It is concluded that the proposed numerical method is effective for hydroplaning simulation. Numerical examples are also presented in which the present simulation methods are applied to newly developed prototype tires.

Hydroplaning Analysis by FEM and FVM: Effect of Tire Rolling and Tire Pattern on Hydroplaning

2000 ◽  
Vol 28 (3) ◽  
pp. 140-156 ◽  
Author(s):  
E. Seta ◽  
Y. Nakajima ◽  
T. Kamegawa ◽  
H. Ogawa
Keyword(s):  
Complex Geometry ◽  
Fluid Structure Interaction ◽  
Numerical Procedure ◽  
Local Analysis ◽  
Fluid Viscosity ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Water Films ◽  
Eulerian Formulation ◽  
Volume Method

Abstract We established the new numerical procedure for hydroplaning. We considered the following three important factors; fluid/structure interaction, tire rolling, and practical tread pattern. The tire was analyzed by the finite element method with Lagrangian formulation, and the fluid was analyzed by the finite volume method with Eulerian formulation. Since the tire and the fluid can be modeled separately and their coupling is computed automatically, the fluid/structure interaction of the complex geometry, such as the tire with the tread pattern, can be analyzed. Since we focused the aim of the simulation on dynamic hydroplaning with thick water films, we ignored the effect of fluid viscosity. We verified the predictability of the hydroplaning simulation in the different parameters such as the water flow, the velocity dependence of hydroplaning, and the effect of the tread pattern on hydroplaning. These parameters could be predicted qualitatively. We also developed the procedure of the global-local analysis to apply the hydroplaning simulation to a practical tire tread pattern design, and we found that the sloped block tip is effective in improving hydroplaning performance.

scholarly journals Influence of Eccentricity and Angular Velocity on Force Effects on Rotor of Magnetorheological Damper

2018 ◽  
Vol 180 ◽  
pp. 02091
Author(s):  
Dominik Šedivý ◽  
Petr Ferfecki ◽  
Simona Fialová
Keyword(s):  
Magnetic Induction ◽  
Magnetorheological Damper ◽  
Squeeze Film ◽  
Fluid Viscosity ◽  
Squeeze Film Damper ◽  
Viscous Forces ◽  
Angular Velocities ◽  
Volume Method ◽  
Gap Width ◽  
Made In

This article presents the evaluation of force effects on squeeze film damper rotor. The rotor is placed eccentrically and its motion is translate-circular. The amplitude of rotor motion is smaller than its initial eccentricity. The force effects are calculated from pressure and viscous forces which were measured by using computational modeling. Damper was filled with magnetorheological fluid. Viscosity of this non-Newtonian fluid is given using Bingham rheology model. Yield stress is not constant and it is a function of magnetic induction which is described by many variables. The most important variables of magnetic induction are electric current and gap width between rotor and stator. The simulations were made in finite volume method based solver. The motion of the inner ring of squeeze film damper was carried out by dynamic mesh. Numerical solution was solved for five different initial eccentricities and angular velocities of rotor motion.

Thermodynamic Properties of Fluids

1997 ◽  
Author(s):  
David Jon Furbish
Keyword(s):  
Mechanical Energy ◽  
Fluid Pressure ◽  
Fluid Flows ◽  
Thermal Conditions ◽  
Fluid Viscosity ◽  
Frozen Ground ◽  
Patterned Ground ◽  
Fluid Behavior ◽  
Fluid Properties ◽  
Convective Motions

Fluid behavior in many geological problems is strongly influenced by extant thermal conditions and flow of heat. Recall, for example, that the coefficient A in Glen’s law for ice (3.40) varies over three orders of magnitude with a change in temperature of 50 °C. The effect of this is to strongly modulate the rate of ice deformation for a given level of stress. Recall further that we introduced several fluid properties—fluid compressibility, for example—where we asserted that our purely mechanical developments were incomplete inasmuch as they did not treat effects of varying temperature. The reasons for this will become clear in this chapter, including why it is difficult to maintain isothermal conditions when the pressure of a fluid is changing. In addition, many geological problems involve fluid flows that are induced by effects of variations in thermal conditions over time and space. These include buoyancy-driven convective motions that arise from variations in fluid density associated with variations in temperature (Chapter 16). Specific examples include convective overturning in a magma chamber, which can significantly influence how crystallizing minerals are distributed; convective circulations of water and chemical solutions in a sedimentary basin, which can influence where rock materials are dissolved and where they are precipitated as cements within pores; and convective circulation of water within the active layer above seasonally frozen ground, which may influence where patterned ground develops in periglacial environments. These processes, and viscous flows in general, invariably involve conversions of mechanical energy to heat, or vice versa. So in considering problems involving heat energy, we should recall from introductory chemistry and physics that such conversions can involve work performed on the fluid or its surroundings, and anticipate that the effects of this ought be manifest in fluid behavior. This chapter, then, is concerned with fluid pressure, temperature, and density, and how these variables are related to heat, mechanical energy, and work. We will note in digressions how these macroscopic concepts, like fluid viscosity, often have clear interpretations at a molecular scale based on kinetic theory of matter.

scholarly journals Analysis of the 3D non-linear Stokes problem coupled to transport-diffusion for shear-thinning heterogeneous microscale flows, applications to digital rock physics and mucociliary clearance

2019 ◽  
Vol 53 (4) ◽  
pp. 1083-1124 ◽  
Author(s):  
David Sanchez ◽  
Laurène Hume ◽  
Robin Chatelin ◽  
Philippe Poncet
Keyword(s):  
Complex Geometry ◽  
Stokes Problem ◽  
Real Life ◽  
Coupled Model ◽  
Rock Physics ◽  
Shear Thinning ◽  
Fluid Viscosity ◽  
Domain Modeling ◽  
Time Dependent Domain ◽  
Non Linear

This study provides the analysis of the generalized 3D Stokes problem in a time dependent domain, modeling a solid in motion. The fluid viscosity is a non-linear function of the shear-rate and depends on a transported and diffused quantity. This is a natural model of flow at very low Reynolds numbers, typically at the microscale, involving a miscible, heterogeneous and shear-thinning incompressible fluid filling a complex geometry in motion. This one-way coupling is meaningful when the action produced by a solid in motion has a dominant effect on the fluid. Several mathematical aspects are developed. The penalized version of this problem is introduced, involving the penalization of the solid in a deformable motion but defined in a simple geometry (a periodic domain and/or between planes), which is of crucial interest for many numerical methods. All the equations of this partial differential system are analyzed separately, and then the coupled model is shown to be well-posed and to converge toward the solution of the initial problem. In order to illustrate the pertinence of such models, two meaningful micrometer scale real-life problems are presented: on the one hand, the dynamics of a polymer percolating the pores of a real rock and miscible in water; on the other hand, the dynamics of the strongly heterogeneous mucus bio-film, covering the human lungs surface, propelled by the vibrating ciliated cells. For both these examples the mathematical hypothesis are satisfied.

Microstructures of fiber suspensions in complex geometry

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Chunlei Ruan ◽  
Jie Ouyang
Keyword(s):  
Fiber Orientation ◽  
Molecular Conformation ◽  
Complex Geometry ◽  
Fluid Model ◽  
Transversely Isotropic ◽  
Fiber Suspensions ◽  
Conformation Tensor ◽  
Planar Contraction ◽  
Volume Method ◽  
Nonlinear Elastic

AbstractEvolutions of molecular conformation and fiber orientation in fiber suspensions are investigated by collocated finite volume method on unstructured triangular meshes. FENE-P (Finite Extensible Nonlinear Elastic Dumbbell model with Peterlin’s approximation) model which is microstructure-based is chosen to describe the polymeric matrix and TIF (transversely isotropic fluid) model is used to calculate the fiber contribution in order to realize the coupling of flow and fiber orientation. Microstructures of molecule and fiber are obtained by analyzing the information of molecular conformation tensor and second-order fiber orientation tensor respectively. Two numerical examples are considered, namely, a planar contraction flow and a planar flow past a confined cylinder. Present results are hoping to give more insight into the microscopic details of complex flows and thus be more helpful for industrial application.

scholarly journals Modeling and Analysis of Vehicle Shimmy with Consideration of the Coupling Effects of Vehicle Body

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xiaogao Li ◽  
Ning Zhang ◽  
Xianjian Jin ◽  
Nan Chen
Keyword(s):  
Degrees Of Freedom ◽  
Lagrange Equation ◽  
Dynamic Responses ◽  
Vehicle Body ◽  
Coupling Effects ◽  
Modeling And Analysis ◽  
Front Suspension ◽  
Vehicle Velocity ◽  
Longitudinal Position ◽  
The Relationship

Based on the Lagrange equation, a 9-degrees-of-freedom shimmy model with consideration of the coupling effects between the motions of vehicle body and the shimmy of front wheels and a 5-degrees-of-freedom shimmy model ignoring these coupling effects for a vehicle with double-wishbone independent front suspensions are presented here to study the problem of vehicle shimmy. According to the eigenvalue loci of system’s Jacobian matrix plotted on the complex plane, the Hopf bifurcation characteristics of nonlinear shimmy are studied and the conditions for the generation of limit cycle are analyzed. Numerical calculation and simulation are used to study the dynamic behavior of vehicle shimmy. By comparing the dynamic responses of two different shimmy models, the coupling effects of vehicle body on vehicle shimmy are studied. Finally, the relationship between the amplitude of each DoF and vehicle velocity and the influences of vehicle parameters such as the mass of vehicle body, the longitudinal position of the center of gravity of vehicle body, and the inclination angle of front suspension on shimmy are studied.

scholarly journals A Multimoment Constrained Finite-Volume Model for Nonhydrostatic Atmospheric Dynamics

2013 ◽  
Vol 141 (4) ◽  
pp. 1216-1240 ◽  
Author(s):  
Xingliang Li ◽  
Chungang Chen ◽  
Xueshun Shen ◽  
Feng Xiao
Keyword(s):  
Finite Volume ◽  
Evolution Equations ◽  
Complex Geometry ◽  
High Order ◽  
Computationally Efficient ◽  
Dynamical Core ◽  
Benchmark Tests ◽  
Volume Method ◽  
Further Development ◽  
Mesh Cell

Abstract The two-dimensional nonhydrostatic compressible dynamical core for the atmosphere has been developed by using a new nodal-type high-order conservative method, the so-called multimoment constrained finite-volume (MCV) method. Different from the conventional finite-volume method, the predicted variables (unknowns) in an MCV scheme are the values at the solution points distributed within each mesh cell. The time evolution equations to update the unknown point values are derived from a set of constraint conditions based on the multimoment concept, where the constraint on the volume-integrated average (VIA) for each mesh cell is cast into a flux form and thus guarantees rigorously the numerical conservation. Two important features make the MCV method particularly attractive as an accurate and practical numerical framework for atmospheric and oceanic modeling. 1) The predicted variables are the nodal values at the solution points that can be flexibly located within a mesh cell (equidistant solution points are used in the present model). It is computationally efficient and provides great convenience in dealing with complex geometry and source terms. 2) High-order and physically consistent formulations can be built by choosing proper constraints in view of not only numerical accuracy and efficiency but also underlying physics. In this paper the authors present a dynamical core that uses the third- and the fourth-order MCV schemes. They have verified the numerical outputs of both schemes by widely used standard benchmark tests and obtained competitive results. The present numerical core provides a promising and practical framework for further development of nonhydrostatic compressible atmospheric models.

Theoretical analysis of a hybrid traffic model accounting for safe velocity

2017 ◽  
Vol 31 (11) ◽  
pp. 1750104 ◽  
Author(s):  
Yu-Qing Wang ◽  
Chao-Fan Zhou ◽  
Bo-Wen Yan ◽  
De-Chen Zhang ◽  
Ji-Xin Wang ◽  
...  
Keyword(s):  
Traffic Flow ◽  
Flow Model ◽  
Local Equilibrium ◽  
Density Wave ◽  
Traffic Model ◽  
Safe Driving ◽  
Traffic Flow Model ◽  
Velocity Wave ◽  
Vehicle Velocity ◽  
Global Equilibrium

A hybrid traffic-flow model [Wang–Zhou–Yan (WZY) model] is brought out in this paper. In WZY model, the global equilibrium velocity is replaced by the local equilibrium one, which emphasizes that the modification of vehicle velocity is based on the view of safe-driving rather than the global deployment. In the view of safe-driving, the effect of drivers’ estimation is taken into account. Moreover, the linear stability of the traffic model has been performed. Furthermore, in order to test the robustness of the system, the evolvement of the density wave and the velocity wave of the traffic flow has been numerically calculated.

Using the DLR-F6 Aircraft Model for the Evaluation of the Academic CFD Code “Galatea”

2014 ◽  
Author(s):  
Georgios N. Lygidakis ◽  
Ioannis K. Nikolos
Keyword(s):  
Large Fraction ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Fluid Flows ◽  
Wind Tunnels ◽  
Navier Stokes ◽  
Test Case ◽  
Tetrahedral Elements ◽  
Computational Performance ◽  
Volume Method

Nowadays, the research in the aerospace scientific field relies strongly on CFD (Computational Fluid Dynamics) algorithms, avoiding (initially at least) a large fraction of the extremely time and money consuming experiments in wind tunnels. In this paper such a recently developed academic CFD code, named Galatea, is presented in brief and validated against a benchmark test case. The prediction of compressible fluid flows is succeeded by the relaxation of the Reynolds Averaged Navier-Stokes (RANS) equations, along with appropriate turbulence models (k-ε, k-ω and SST), employed on three-dimensional unstructured hybrid grids, composed of prismatic, pyramidical and tetrahedral elements. For the discretization of the computational field a node-centered finite-volume method is implemented, while for improved computational performance Galatea incorporates an agglomeration multigrid methodology and a suitable parallelization strategy. The proposed algorithm is evaluated against the Wing-Body (WB) and the Wing-Body-Nacelles-Pylons (WBNP) DLR-F6 aircraft configurations, demonstrating its capability for a good performance in terms of accuracy and geometric flexibility.

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