Thermo-Hydrodynamic Model Influence on First Order Coefficients in Turbocharger Thrust Bearings

2018 ◽  
pp. 16-31
Author(s):  
Thales Freitas Peixoto ◽  
Gregory Bregion Daniel ◽  
Katia Lucchesi Cavalca
Keyword(s):  
Hydrodynamic Model ◽  
Thrust Bearings ◽  
First Order

scholarly journals Hydrodynamic Model Of Glaciers and Ice Sheets Interacted With Ocean

1990 ◽  
Vol 14 ◽  
pp. 347-347
Author(s):  
V.L. Mazo
Keyword(s):  
Shear Stress ◽  
Hydrodynamic Model ◽  
Evolution Equations ◽  
Three Dimensional ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Longitudinal Stress ◽  
First Order ◽  
Longwave Approximation ◽  
Different Parts

Tidewater glaciers and large ice sheets, e.g. the Antarctic ice sheet and a late-Würm Arctic ice sheet, are complex but single dynamic systems composed of terrestrial, marine and floating parts. Morphology and dynamics of the different parts are different. The terrestrial parts are convex and their dynamics are controlled by shear stress only (the longitudinal stress is zero); the floating parts are concave and their dynamics are controlled by longitudinal stress only (the shear stress is zero). To connect the different parts we should consider transitional zones where shear and longitudinal stresses are comparable.To describe glacier and ice-sheet dynamics, longwave approximation of the first order is used. In this approximation it is impossible to connect terrestrial and floating parts dynamically, only morphologically and kinematically. It means that the first-order longwave approximation is not sufficient.If the transitional zone between the terrestrial and floating parts is long in comparison to ice thickness (in hydrodynamics the term “weak” is used) we can do the next step in the longwave approximation to describe the single dynamical system consisting of the terrestrial and floating parts and the weak transitional zones (ice streams). It is a purely hydrodynamical approach to the problem without ad hoc hypothesis.The presented model is a non-stationary three-dimensional hydrodynamic model of glaciers and ice sheets interacted with ocean, involving the conditions of ice continuity and dynamic equilibrium, ice rheology, and boundary conditions on the free surface (dynamic and kinematic) and on the bed (ice freezing or sliding). Longwave approximation is used to reduce the three-dimensional model to a two-dimensional one. The latter consists of (1) evolution equations for grounded and floating parts and weak transitional zones; (2) boundary conditions on the fronts (e.g. the conditions of calving); (3) equations governing the junctions of the parts (the most important junction is the grounded line) with the conditions connecting the evolution equations.

scholarly journals Hydrodynamic Model Of Glaciers and Ice Sheets Interacted With Ocean

1990 ◽  
Vol 14 ◽  
pp. 347
Author(s):  
V.L. Mazo
Keyword(s):  
Shear Stress ◽  
Hydrodynamic Model ◽  
Evolution Equations ◽  
Three Dimensional ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Longitudinal Stress ◽  
First Order ◽  
Longwave Approximation ◽  
Different Parts

Tidewater glaciers and large ice sheets, e.g. the Antarctic ice sheet and a late-Würm Arctic ice sheet, are complex but single dynamic systems composed of terrestrial, marine and floating parts. Morphology and dynamics of the different parts are different. The terrestrial parts are convex and their dynamics are controlled by shear stress only (the longitudinal stress is zero); the floating parts are concave and their dynamics are controlled by longitudinal stress only (the shear stress is zero). To connect the different parts we should consider transitional zones where shear and longitudinal stresses are comparable. To describe glacier and ice-sheet dynamics, longwave approximation of the first order is used. In this approximation it is impossible to connect terrestrial and floating parts dynamically, only morphologically and kinematically. It means that the first-order longwave approximation is not sufficient. If the transitional zone between the terrestrial and floating parts is long in comparison to ice thickness (in hydrodynamics the term “weak” is used) we can do the next step in the longwave approximation to describe the single dynamical system consisting of the terrestrial and floating parts and the weak transitional zones (ice streams). It is a purely hydrodynamical approach to the problem without ad hoc hypothesis. The presented model is a non-stationary three-dimensional hydrodynamic model of glaciers and ice sheets interacted with ocean, involving the conditions of ice continuity and dynamic equilibrium, ice rheology, and boundary conditions on the free surface (dynamic and kinematic) and on the bed (ice freezing or sliding). Longwave approximation is used to reduce the three-dimensional model to a two-dimensional one. The latter consists of (1) evolution equations for grounded and floating parts and weak transitional zones; (2) boundary conditions on the fronts (e.g. the conditions of calving); (3) equations governing the junctions of the parts (the most important junction is the grounded line) with the conditions connecting the evolution equations.

Dynamic Characteristics of Aerostatic Thrust Bearings with Porous Inserts

1980 ◽  
Vol 22 (2) ◽  
pp. 55-58 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Perturbation Method ◽  
Dynamic Characteristics ◽  
Dynamic Behaviour ◽  
Thrust Bearing ◽  
Thrust Bearings ◽  
First Order ◽  
Design Variables ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
First Order Perturbation

A first-order perturbation method is adopted to find the dynamic behaviour of an aerostatic circular thrust bearing having a central porous insert as a restrictor. The linearized gas film stiffness and damping are derived and used to study their behaviour with other design variables.

scholarly journals DIFFUSION IN A CONTINUUM MODEL OF SELF-PROPELLED PARTICLES WITH ALIGNMENT INTERACTION

2010 ◽  
Vol 20 (supp01) ◽  
pp. 1459-1490 ◽  
Author(s):  
PIERRE DEGOND ◽  
TONG YANG
Keyword(s):  
Hydrodynamic Model ◽  
Continuum Model ◽  
Momentum Conservation ◽  
Biological Agents ◽  
Quadratic Functions ◽  
Enskog Theory ◽  
First Order ◽  
Derivation Method ◽  
Derivatives Of ◽  
Alignment Interaction

In this paper, we provide the O(ε) corrections to the hydrodynamic model derived by Degond and Motsch from a kinetic version of the model by Vicsek and co-authors describing flocking biological agents. The parameter ε stands for the ratio of the microscopic to the macroscopic scales. The O(ε) corrected model involves diffusion terms in both the mass and velocity equations as well as terms which are quadratic functions of the first-order derivatives of the density and velocity. The derivation method is based on the standard Chapman–Enskog theory, but is significantly more complex than usual due to both the non-isotropy of the fluid and the lack of momentum conservation.

On the Influence of Thrust Bearings on the Nonlinear Rotor Vibrations of Turbochargers

2016 ◽  
Author(s):  
Ioannis Chatzisavvas ◽  
Aydin Boyaci ◽  
Andreas Lehn ◽  
Marcel Mahner ◽  
Bernhard Schweizer ◽  
...  
Keyword(s):  
Hydrodynamic Model ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Oil Viscosity ◽  
Oil Film ◽  
Thrust Bearings ◽  
Run Up ◽  
Generalized Reynolds Equation

This work investigates the influence of hydrodynamic thrust bearings on the lateral rotor oscillations. Four thrust bearing models are compared in terms of their predictions of the oil-film pressure (Reynolds equation), the oil-film temperature (energy equation) and the load capacity. A detailed thrust bearing model using the generalized Reynolds equation and the 3D energy equation, a model using the standard Reynolds equation with a 2D energy equation, a model where the standard Reynolds equation and the 2D energy equation are decoupled and finally an isothermal thrust bearing model are presented. It is shown that in lower rotational speeds, the four models produce almost the same results. However, as the rotational speed is increased, the necessity for a thermo-hydrodynamic model is demonstrated. Run-up simulations of a turbocharger rotor/bearing system are performed, using an isothermal thrust bearing model with different inlet oil-temperatures. The influence of the oil-temperature of the thrust bearing on the subsynchronous rotor oscillations is investigated. Finally, a thermo-hydrodynamic model is compared with an isothermal in run-up simulations, where the influence of the variable oil-viscosity is discussed.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

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