A Note on Leakage Jet Forces: Application in the Modelling of Digital Twins of Hydraulic Valves

2021 ◽  
Author(s):  
Zoufiné Lauer-Baré ◽  
Erich Gaertig ◽  
Johannes Krebs ◽  
Christian Arndt ◽  
Christian Sleziona ◽  
...  
Keyword(s):  
Shear Force ◽  
Analytical Approximation ◽  
Analytical Relation ◽  
Large Set ◽  
Simulation Tools ◽  
Eccentric Cylinders ◽  
Digital Twins ◽  
Numerical Instabilities ◽  
Flow Through ◽  
Hydraulic Valves

The proper modelling of fluid flow through annular gaps is of great interest in leakage calculations for many applications in fluid power technology. However, while detailed numerical simulations are certainly possible, they are very time consuming, in various cases prone to numerical instabilities and may not even include all physically relevant effects. This is an issue especially in system simulations, where a large set of computations is needed in order to prepare the lookup-tables for the required input fields. In this work, an analytical approximation for the shear force, which is induced by viscous flow between two eccentric cylinders, is presented. This relation, and its derivation, mimics and enhances the well-known Piercy-relation for the corresponding volume flow that is utilized in state-of-the-art system simulation tools. To determine its range of validity, the analytical relation for the shear force is compared to 3D-simulations. Additionally, an application of this approximation for creating digital twins of hydraulic valves is also discussed in this work.

Effect of vane thickness on radiometric force

2013 ◽  
Vol 735 ◽  
pp. 684-704 ◽  
Author(s):  
Austin Ventura ◽  
Natalia Gimelshein ◽  
Sergey Gimelshein ◽  
Andrew Ketsdever
Keyword(s):  
Experimental Study ◽  
Pressure Difference ◽  
Shear Force ◽  
Vortex Flow ◽  
Lateral Side ◽  
Height Ratio ◽  
Flow Through ◽  
Cold Chamber ◽  
Different Thickness ◽  
Radiometric Forces

AbstractA numerical and experimental study of radiometric forces on vanes of different thickness is presented for the flow regime where the radiometric force is near its maximum. For single- and multi-vane geometries, it is shown that radiometric force decreases by only ∼10–15 % when the vane thickness-to-height ratio increases fourfold from 0.5 to 2. For a single-vane geometry, the shear force on the lateral side of the vane is attributed to a vortex flow generated by the interaction of cold chamber walls and heated walls of the vane. In that case, it always acts to reduce the total radiometric force governed by the pressure difference between the hot and the cold sides of the vane. For a multi-vane geometry, represented by a perforated vane, the shear force becomes positive for larger thickness-to-height ratios and lower pressures, primarily due to strong vane-driven transpiration flow through the gaps.

scholarly journals Pressure Drop Measurements of the Flow through Eccentric Cylinders with Rotating Inner Cylinders

1969 ◽  
Vol 12 (53) ◽  
pp. 1032-1040 ◽  
Author(s):  
Yutaka YAMADA ◽  
Koichi NAKABAYASHI ◽  
Kozo MAEDA
Keyword(s):  
Pressure Drop ◽  
Eccentric Cylinders ◽  
Flow Through

scholarly journals Rotational and Axial Flow through the Gap between Eccentric Cylinders, of which the Outer One Rotates

1974 ◽  
Vol 17 (114) ◽  
pp. 1564-1571 ◽  
Author(s):  
Koichi NAKABAYASHI ◽  
Yutaka YAMADA ◽  
Kaname SEO
Keyword(s):  
Axial Flow ◽  
Eccentric Cylinders ◽  
Flow Through

THE INFLUENCE OF HUMIDITY ON THE SHEAR FORCE BETWEEN TIP AND SAMPLE IN NSOM USING PIEZOELECTRIC FORK

2005 ◽  
Vol 12 (03) ◽  
pp. 355-358
Author(s):  
TIANHAO ZHANG ◽  
ZHEYU FANG ◽  
JIANYA ZHENG ◽  
LIMO GAO ◽  
HAIDONG YANG ◽  
...  
Keyword(s):  
Shear Force ◽  
Current Flow ◽  
Optic Fiber ◽  
Physical Origin ◽  
Fiber Probe ◽  
Vibration Equation ◽  
Environmental Humidity ◽  
Cohesion Force ◽  
Flow Through ◽  
Sample System

The distance between tip and sample can be regulated using piezoelectric quartz fork glued with micro optic fiber probe. A biquadrate vibration equation for the fork–probe–sample system is established to theoretically analyze the relations of the electric current flow through fork versus tip–sample (T–S) distance (I–d). The I–d curve and the action distance for shear force are influenced by environmental humidity. The results reinforce the opinions in the earlier works by other researches that the physical origin of the shear force is due to a material filling the tip–sample gap. Furthermore, the intrinsic reasons for shear force damping between tip and sample have been confirmed and developed, i.e. the water and hydrocarbon coupled between optic fiber probe and sample due to the capillary cohesion force.

The bovine teat canal: information from measurement of velocity of milk flow from the teat

1986 ◽  
Vol 53 (2) ◽  
pp. 179-185 ◽  
Author(s):  
David M. Williams ◽  
Graeme A. Mein
Keyword(s):  
Mass Flow Rate ◽  
Flow Rate ◽  
Shear Force ◽  
Peak Flow ◽  
Effective Diameter ◽  
Peak Flow Rate ◽  
Milk Flow ◽  
Rate Period ◽  
Flow Through ◽  
Teat Canal

SUMMARYThe velocity of milk flow from the teat during the peak flow rate period of milking was estimated to be ∼ 8·5 m/s with a liner vacuum of 50 kPa and 7·5 m/s at 40 kPa. These results confirm the applicability of the Bernoulli theorem for estimating velocity of milk flow through the teat canal during milking. Concurrent measurements of mass flow rate and velocity indicate that the effective diameter of the open teat canal is ∼ 2 mm. Further calculations indicate that the shear force due to milk flow acting to debride the surface of the open teat canal is about 1·8 × 10-2 N. The opposing surfaces of the ‘closed’ teat canal may be ∼ 100 µm apart immediately after milking. If so, bacteria present in the milk residue within the teat canal would never be more than 50 µm from a surface.

scholarly journals Estimating Vehicle Suspension Characteristics for Digital Twin Creation with Genetic Algorithm

2021 ◽  
Author(s):  
Tamás Ormándi ◽  
Balázs Varga ◽  
Tamás Tettamanti
Keyword(s):  
Genetic Algorithm ◽  
Vehicle Dynamics ◽  
Mixed Reality ◽  
Autonomous Vehicle ◽  
Vehicle Suspension ◽  
Simulation Tools ◽  
Whole Process ◽  
Simulation Techniques ◽  
Digital Twins ◽  
Adequate Quality

Usage of simulation techniques like Vehicle-in-the-Loop, Scenario-in-the-Loop, and other mixed-reality systems are becoming inevitable in autonomous vehicle development, particularly in testing and validation. These methods rely on using digital twins, realistic representations of real vehicles, and traffic in a carefully rebuilt virtual world. Recreating them precisely in a virtual ecosystem requires many parameters of real vehicles to follow their properties in a simulation. This is especially true for vehicle dynamics, where these parameters have high impact on the simulation results. The paper's objective is to provide a method that can help reverse engineering a real car's suspension characteristics with the help of a genetic algorithm. A detailed description of the method is presented, guiding the reader through the whole process, including the meta-heuristic function's settings and how it interfaces with IPG Carmaker. The paper also presents multiple measurements, which can be effortlessly recreated without expensive devices or the need to disassemble any vehicle parts. Measurements are reproduced in two separate simulation tools with special scenarios providing an efficient way to analyze and verify the results. The provided method creates vehicle suspension characteristics with adequate quality, opening up the possibility to use them in the creation of digital twins or creating virtual traffic with realistic vehicle dynamics for high-quality visualization. Results show satisfying accuracy when tested with OpenCRG.

PARTICULATE SUSPENSION FLOW INDUCED BY SINUSOIDAL PERISTALTIC WAVES THROUGH ECCENTRIC CYLINDERS: THREAD ANNULAR

2013 ◽  
Vol 06 (04) ◽  
pp. 1350026 ◽  
Author(s):  
KH. S. MEKHEIMER ◽  
Y. ABD ELMABOUD ◽  
A. I. ABDELLATEEF
Keyword(s):  
Particle Concentration ◽  
Surgical Trauma ◽  
Medical Implants ◽  
Flexible Cylinder ◽  
Fluid Mixture ◽  
Friction Forces ◽  
Eccentric Cylinders ◽  
Peristaltic Pumping ◽  
Flow Through ◽  
Eccentric Annuli

This paper describes a new model for obtaining analytical solutions of peristaltic flow through eccentric annuli. A mathematical model of peristaltic pumping of a fluid mixture (as blood model) in a circular eccentric cylinders is presented and it is motivated due to the fact that thread injection is a promising method for placing medical implants within the human body with minimum surgical trauma. For the eccentric annuli, the inner cylinder is rigid and moving with a constant velocity V, and the outer one is hollow flexible cylinder that has a sinusoidal wave traveling down its wall. The coupled differential equations for both the fluid and the particle phases have been solved by using two methods and the expressions for the velocity distribution of fluid and particle phase, flow rate, pressure drop, friction forces at the inner and outer cylinders have been derived. The results obtained are discussed in brief. The significance of the particle concentration and the eccentricity parameter as well as the nature of the basic flow has been well explained.

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