scholarly journals Numerical Study of Hydrodynamic Forces for AFM Operations in Liquid

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Tobias Berthold ◽  
Guenther Benstetter ◽  
Werner Frammelsberger ◽  
Rosana Rodríguez ◽  
Montserrat Nafría
Keyword(s):  
Drag Force ◽  
Numerical Study ◽  
Viscous Friction ◽  
Hydrodynamic Drag ◽  
Water Mixture ◽  
Ultrapure Water ◽  
Liquid Environment ◽  
Drag Forces ◽  
Organic Sample ◽  
Repulsive Forces

For advanced atomic force microscopy (AFM) investigation of chemical surface modifications or very soft organic sample surfaces, the AFM probe tip needs to be operated in a liquid environment because any attractive or repulsive forces influenced by the measurement environment could obscure molecular forces. Due to fluid properties, the mechanical behavior of the AFM cantilever is influenced by the hydrodynamic drag force due to viscous friction with the liquid. This study provides a numerical model based on computational fluid dynamics (CFD) and investigates the hydrodynamic drag forces for different cantilever geometries and varying fluid conditions for Peakforce Tapping (PFT) in liquids. The developed model was verified by comparing the predicted values with published results of other researchers and the findings confirmed that drag force dependence on tip speed is essentially linear in nature. We observed that triangular cantilever geometry provides significant lower drag forces than rectangular geometry and that short cantilever offers reduced flow resistance. The influence of different liquids such as ultrapure water or an ethanol-water mixture as well as a temperature induced variation of the drag force could be demonstrated. The acting forces are lowest in ultrapure water, whereas with increasing ethanol concentrations the drag forces increase.

scholarly journals Numerical study of the hydrodynamic drag force in atomic force microscopy measurements undertaken in fluids

Micron ◽  
2014 ◽  
Vol 66 ◽  
pp. 37-46 ◽  
Author(s):  
J.V. Méndez-Méndez ◽  
M.T. Alonso-Rasgado ◽  
E. Correia Faria ◽  
E.A. Flores-Johnson ◽  
R.D. Snook
Keyword(s):  
Atomic Force Microscopy ◽  
Drag Force ◽  
Numerical Study ◽  
Hydrodynamic Drag ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Numerical study on the hydrodynamic drag force of a container ship model

2019 ◽  
Vol 58 (3) ◽  
pp. 849-859 ◽  
Author(s):  
Ahmed G. Elkafas ◽  
Mohamed M. Elgohary ◽  
Akram E. Zeid
Keyword(s):  
Drag Force ◽  
Numerical Study ◽  
Hydrodynamic Drag ◽  
Container Ship ◽  
Ship Model

An Alternative Stochastic Representation of Drag Forces on Offshore Structures for Dynamic Analyses

1997 ◽  
Vol 119 (3) ◽  
pp. 178-183 ◽  
Author(s):  
A. Naess ◽  
L. J. Ho̸egh Krohn ◽  
A. A. Pisano
Keyword(s):  
Drag Force ◽  
Offshore Structures ◽  
Irregular Waves ◽  
Distinct Advantage ◽  
Hydrodynamic Drag ◽  
Standard Formulation ◽  
Stochastic Representation ◽  
Drag Forces ◽  
Zero Current ◽  
Dynamic Analyses

A new method for stochastic representation of the hydrodynamic drag forces on offshore structures subjected to irregular waves is described. For the case of zero current, it is shown that it is possible to construct a genuinly quadratic representation of the drag force that reproduces the statistical properties of the standard formulation of the drag force closely, and which has a spectral density that approximates the desired force spectrum reasonably well. The distinct advantage of this representation is that it brings dynamic analysis back into the frequency domain, in a similar manner as achieved for a linearized force representation.

OUTDOOR TESTS OF A TOWED BOAT MODEL WITH FUEL COMBUSTION IN A BOTTOM CAVITY

2020 ◽  
Author(s):  
S. M. FROLOV ◽  
◽  
S. V. Platonov ◽  
K. A. AVDEEV ◽  
V. S. AKSENOV ◽  
...  
Keyword(s):  
Drag Force ◽  
Direct Contact ◽  
Propulsion System ◽  
Hydrodynamic Drag ◽  
Atmospheric Air ◽  
System A ◽  
Bottom Cavity ◽  
Gas Cavity ◽  
System Power ◽  
Gas Supply

To reduce the hydrodynamic drag force to the movement of the boat, an artificial gas cavity is organized under its bottom. Such a cavity partially insulates the bottom from direct contact with water and provides “gas lubrication” by means of forced supply of atmospheric air or exhaust gases from the main propulsion system. A proper longitudinal and transverse shaping of the gas cavity can significantly (by 20%-30%) reduce the hydrodynamic drag of the boat at low (less than 3%) consumption of the propulsion system power for gas supply.

scholarly journals Electrodynamics of a magnet moving through a conducting pipe

2006 ◽  
Vol 84 (4) ◽  
pp. 253-271 ◽  
Author(s):  
M Hossein Partovi ◽  
Eliza J Morris
Keyword(s):  
Drag Force ◽  
Eddy Currents ◽  
Numerical Study ◽  
Full Range ◽  
Magnetic Behavior ◽  
Integral Form ◽  
Asymptotic Formulas ◽  
Pipe Material ◽  
Point Dipole ◽  
Axially Symmetric

The popular demonstration involving a permanent magnet falling through a conducting pipe is treated as an axially symmetric boundary-value problem. Specifically, Maxwell's equations are solved for an axially symmetric magnet moving coaxially inside an infinitely long, conducting cylindrical shell of arbitrary thickness at nonrelativistic speeds. Analytic solutions for the fields are developed and used to derive the resulting drag force acting on the magnet in integral form. This treatment represents a significant improvement over existing models, which idealize the problem as a point dipole moving slowly inside a pipe of negligible thickness. It also provides a rigorous study of eddy currents under a broad range of conditions, and can be used for magnetic braking applications. The case of a uniformly magnetized cylindrical magnet is considered in detail, and a comprehensive analytical and numerical study of the properties of the drag force is presented for this geometry. Various limiting cases of interest involving the shape and speed of the magnet and the full range of conductivity and magnetic behavior of the pipe material are investigated and corresponding asymptotic formulas are developed.PACS Nos.: 81.70.Ex, 41.20.–q, 41.20.Gz

Experimental and Numerical Study of Methanol-Water Mixture Single-Phase Heat Transfer in a Micro-Channel Heat Sink

2012 ◽  
Author(s):  
Chun K. Kwok ◽  
Matthew M. Asada ◽  
Jonathan R. Mita ◽  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Numerical Study ◽  
Pure Water ◽  
Molar Fraction ◽  
Water Mixture ◽  
Micro Channel ◽  
Numerical Predictions

This paper presents an experimental study of single-phase heat transfer characteristics of binary methanol-water mixtures in a micro-channel heat sink containing an array of 22 microchannels with 240μm × 630μm cross-section. Pure water, pure methanol, and five methanol-water mixtures with methanol molar fraction of 16%, 36%, 50%, 63% and 82% were tested. Key parametric trends were identified and discussed. The experimental study was complemented by a three-dimensional numerical simulation. Numerical predictions and experimental data are in good agreement with a mean absolute error (MAE) of 0.87%.

Slip Length Measurement of Water Flow on Graphite Surface Using Atomic Force Microscope

2014 ◽  
Vol 941-944 ◽  
pp. 1581-1584 ◽  
Author(s):  
Da Yong Li ◽  
Da Lei Jing ◽  
Yun Lu Pan ◽  
Khurshid Ahmad ◽  
Xue Zeng Zhao
Keyword(s):  
Atomic Force Microscope ◽  
Water Flow ◽  
Drag Force ◽  
Silicon Surface ◽  
Slip Length ◽  
Graphite Surface ◽  
Length Measurement ◽  
Hydrodynamic Drag ◽  
Experimental Measurements ◽  
Atomic Force

In this paper, we present experimental measurements of slip length of deionized (DI) water flow on a silicon surface and a graphite surface by using atomic force microscope. The results show that the measured hydrodynamic drag force is higher on silicon surface than that on graphite surface, and a measured slip length about 10 nm is obtained on the later surface.

scholarly journals A numerical study of microparticle acoustophoresis driven by acoustic radiation forces and streaming-induced drag forces

Lab on a Chip ◽  
2012 ◽  
Vol 12 (22) ◽  
pp. 4617 ◽  
Author(s):  
Peter Barkholt Muller ◽  
Rune Barnkob ◽  
Mads Jakob Herring Jensen ◽  
Henrik Bruus
Keyword(s):  
Acoustic Radiation ◽  
Numerical Study ◽  
Drag Forces ◽  
Induced Drag ◽  
Radiation Forces

Hydrodynamic drag in steller sea lions (Eumetopias jubatus)

2000 ◽  
Vol 203 (12) ◽  
pp. 1915-1923 ◽  
Author(s):  
L.L. Stelle ◽  
R.W. Blake ◽  
A.W. Trites
Keyword(s):  
Minimum Cost ◽  
The Body ◽  
Hydrodynamic Drag ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
California Sea Lions ◽  
Cost Of Transport ◽  
Sea Lions ◽  
Drag Forces ◽  
The Individual

Drag forces acting on Steller sea lions (Eumetopias jubatus) were investigated from ‘deceleration during glide’ measurements. A total of 66 glides from six juvenile sea lions yielded a mean drag coefficient (referenced to total wetted surface area) of 0.0056 at a mean Reynolds number of 5.5×10(6). The drag values indicate that the boundary layer is largely turbulent for Steller sea lions swimming at these Reynolds numbers, which are past the point of expected transition from laminar to turbulent flow. The position of maximum thickness (at 34 % of the body length measured from the tip of the nose) was more anterior than for a ‘laminar’ profile, supporting the idea that there is little laminar flow. The Steller sea lions in our study were characterized by a mean fineness ratio of 5.55. Their streamlined shape helps to delay flow separation, reducing total drag. In addition, turbulent boundary layers are more stable than laminar ones. Thus, separation should occur further back on the animal. Steller sea lions are the largest of the otariids and swam faster than the smaller California sea lions (Zalophus californianus). The mean glide velocity of the individual Steller sea lions ranged from 2.9 to 3.4 m s(−)(1) or 1.2-1.5 body lengths s(−)(1). These length-specific speeds are close to the optimum swim velocity of 1.4 body lengths s(−)(1) based on the minimum cost of transport for California sea lions.

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