Added-Mass Effect in Modeling of Cilia-Based Devices for Microfluidic Systems

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
J. Kongthon ◽  
B. McKay ◽  
D. Iamratanakul ◽  
K. Oh ◽  
J.-H. Chung ◽  
...  
Keyword(s):  
Drag Force ◽  
Vibrational Frequency ◽  
Hydrodynamic Interaction ◽  
Substantial Reduction ◽  
Fluid Flows ◽  
Mass Effect ◽  
Added Mass ◽  
Hydrodynamic Drag ◽  
Vibrational Dynamics ◽  
Inertial Loading

This article shows that the added mass due to fluid-structure interaction significantly affects the vibrational dynamics of cilia-based (vibrating cantilever-type) devices for handling microscale fluid flows. Commonly, the hydrodynamic interaction between the cilia-based actuators and fluid is modeled as a drag force that results in damping of the cilia motion. Our main contribution is to show that such damping effects cannot explain the substantial reduction in the resonant-vibrational frequency of the cilia actuator operating in liquid when compared with the natural frequency of the cilia in air. It is shown that an added-mass approach (that accounts for the inertial loading of the fluid) can explain this reduction in the resonant-vibrational frequency when operating cantilever-type devices in liquids. Additionally, it is shown that the added-mass effect can explain why the cilia-vibration amplitude is not substantially reduced in a liquid by the hydrodynamic drag force. Thus, this article shows the need to model the added-mass effect, both theoretically and by using experimental results.

Added-Mass Effect in Modeling of Cilia-Based Devices for Microfluidic Systems

2010 ◽  
Author(s):  
J. Kongthon ◽  
B. McKay ◽  
D. Iamratanakul ◽  
K. Oh ◽  
J.-H. Chung ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Vibration Amplitude ◽  
Vibrational Frequency ◽  
Substantial Reduction ◽  
Mass Effect ◽  
Added Mass ◽  
Hydrodynamic Drag ◽  
Vibrational Dynamics ◽  
Structure Interaction ◽  
Inertial Loading

This article shows that the added mass due to fluid structure interaction significantly affects the vibrational dynamics of cilia-based devices. Our main contribution is to show that such damping effects cannot explain the substantial reduction in the resonant vibrational frequency of the cilia operating in liquid when compared to the natural frequency of the cilia in air. It is shown that an added-mass approach (that accounts for the inertial loading of the fluid) can explain this reduction in the resonant vibrational frequency when operating the cantilever-type devices in liquids. Additionally, it is shown that the added-mass effect can explain why the cilia-vibration amplitude is not substantially reduced in a liquid by the hydrodynamic drag force. Thus, this article shows the need to model the added-mass effect, both, theoretically and by using experimental results.

Added-Mass Effect in Modeling of Cilia-Based (Vibrating Cantilever-Type) Devices for Microfluidic Systems

2007 ◽  
Author(s):  
B. McKay ◽  
D. Iamratanakul ◽  
K. Oh ◽  
J.-H. Chung ◽  
J. Riley ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Natural Frequency ◽  
Hydrodynamic Interaction ◽  
Substantial Reduction ◽  
Fluid Flows ◽  
Mass Effect ◽  
Added Mass ◽  
Drag Effect ◽  
Vibrational Dynamics ◽  
Structure Interaction

This article shows that the added mass due to fluid structure interaction significantly affects the vibrational dynamics of cilia-based (vibrating cantilever-type) devices for handling micro/nano-scale fluid flows. Commonly, the hydrodynamic interaction between the cilia-based actuator and fluid is modeled as a Stokes drag force that is proportional to the velocity. Our main contribution is to show that such a drag effect cannot explain the substantial reduction in the resonant frequency of the cilia actuator operating in liquid when compared to the natural frequency of the cilia in air. It is shown that an added-mass approach can explain this reduction in the resonant frequency when operating cantilever-type devices in fluid. Thus, this article shows the need to model the added-mass effect, both, theoretically and by using experimental results.

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.

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.

Fluid Added Mass Effect in the Modal Response of a Pump-Turbine Impeller

2009 ◽  
Author(s):  
Eduard Egusquiza ◽  
Carme Valero ◽  
Quanwei Liang ◽  
Miguel Coussirat ◽  
Ulrich Seidel
Keyword(s):  
Natural Frequencies ◽  
Experimental Tests ◽  
Mass Effect ◽  
Added Mass ◽  
Mode Shapes ◽  
Pump Turbine ◽  
Modal Response ◽  
Surrounding Fluid ◽  
Turbine Impeller ◽  
Good Agreement

In this paper, the reduction in the natural frequencies of a pump-turbine impeller prototype when submerged in water has been investigated. The impeller, with a diameter of 2.870m belongs to a pump-turbine unit with a power of around 100MW. To analyze the influence of the added mass, both experimental tests and numerical simulations have been carried out. The experiment has been performed in air and in water. From the frequency response functions the modal characteristics such as natural frequencies and mode shapes have been obtained. A numerical simulation using FEM (Finite Elements Model) was done using the same boundary conditions as in the experiment (impeller in air and surrounded by a mass of water). The modal behaviour has also been calculated. The numerical results were compared with the available experimental results. The comparison shows a good agreement in the natural frequency values both in air and in water. The reduction in frequency due to the added mass effect of surrounding fluid has been calculated. The physics of this phenomenon due to the fluid structure interaction has been investigated from the analysis of the mode-shapes.

The effect and site of action of potassium upon magnesium absorption in sheep

1976 ◽  
Vol 27 (6) ◽  
pp. 873 ◽  
Author(s):  
FM Tomas ◽  
BJ Potter
Keyword(s):  
Potassium Chloride ◽  
Rumen Fluid ◽  
Substantial Reduction ◽  
Urine Volume ◽  
Fluid Flows ◽  
Basal Diet ◽  
Major Effect ◽  
Urinary Potassium ◽  
Bioelectrical Potential ◽  
Plasma Magnesium

The effect of potassium chloride infusion to the rumen or duodenum of sheep upon the absorption of magnesium from the stomach and intestinal regions has been examined. Three Merino ewes, each prepared with a cannula into the rumen and a re-entrant cannula into the duodenum, were offered a basal diet (control) which provided 46.3–51.1 mmoles magnesium and 299–320 mmoles potassium per day. Potassium chloride (500–800 mmoles/day) was infused continuously to either the rumen or duodenum. Digesta fluid flows were estimated from the dilution of a Cr-EDTA solution continuously infused to the rumen. Potassium infusion to either gastrointestinal site led to a comparable increase in the water intake, urine volume and levels of plasma and urinary potassium. Infusion to the rumen caused a marked increase in the potassium levels and a decrease in sodium levels in rumen fluid, as well as an increase in the rumen fluid to blood bioelectrical potential. No effect of treatment on digesta fluid flows was observed. Net magnesium absorption was lowered only when potassium was infused to the rumen, and the reduction was almost entirely due to reduced absorption of magnesium from the stomach. There was no consistent effect on absorption of magnesium from the intestines. Plasma magnesium levels were lowered by both the intraruminal infusion and, to a lesser extent, the duodenal infusion of potassium. The results indicate that although one consequence of potassium ingestion by sheep may be an enhancement of the urinary excretion of magnesium, the major effect on magnesium metabolism is a substantial reduction of absorption of magnesium from the reticulorumen.

An Investigation to Added Mass Force on the Wing of Insect Inspired from a Rigid Sphere Model

2012 ◽  
Vol 476-478 ◽  
pp. 2485-2488
Author(s):  
Mei Jun Hu ◽  
Xing Yao Yan ◽  
Jin Yao Yan
Keyword(s):  
Insect Flight ◽  
Aerodynamic Force ◽  
Mass Effect ◽  
Added Mass ◽  
Rigid Sphere ◽  
Force Model ◽  
Mass Force ◽  
Real Time Control ◽  
Wing Model ◽  
Force Peak

There is a force peak at the beginning of each stroke during the insect flight, this force peak contributes a lot to the total aerodynamic force. To build a man made insect inspired man-made micro aero vehicle, this force need to be considered in the aero force model, and this model should as simple as possible in order to be used in feedback real-time control. Here we presented a simplified model to take the medium added mass effect of the wing into account. Simulated results show a high force peak at the beginning of each stroke and are quite similar to the measured forces on the physical wing model which were carried out by Dickinson et.al.

scholarly journals Structural seismic characteristics assessment of LMFR fuel assembly hexagonal wrapper over operational temperature range

2019 ◽  
Vol 34 (4) ◽  
pp. 313-324
Author(s):  
M. Khizer ◽  
Zhang Yong ◽  
Yang Guowei ◽  
Wu Qingsheng ◽  
Wu Yican
Keyword(s):  
Fuel Assembly ◽  
Fast Reactor ◽  
Natural Frequencies ◽  
Mass Effect ◽  
Added Mass ◽  
Reactor Fuel ◽  
Temperature Range ◽  
Fast Reactor Fuel ◽  
Lead Bismuth Eutectic ◽  
Reactor Fuel Assembly

In this study, the structural integrity of liquid metal fast reactor fuel assembly has been established for different parameters considering the optimum fuel design. Analytical calculation of added mass effect due to lead bismuth eutectic and verification through previously presented theories, has been established. The integrity of the hexagonal wrapper of fuel assembly has been guaranteed over the entire operating temperature range. Effect of temperature on the density of lead bismuth eutectic, the subsequent change in added mass of lead bismuth eutectic, the effect on natural frequencies and effect on stresses on wrapper, has been studied in detail. A simple empirical relationship is presented for estimation of added mass effect for lead bismuth eutectic type fast reactors for any desired temperature. An approach for assessment of fast reactor fuel assembly performance has been outlined and calculated results are presented. Nuclear seismic rules require that systems and components which are important to safety, shall be capable of bearing earthquake effects and their integrity and functionality should be guaranteed. Mode shapes, natural frequencies, stresses on wrapper and seismic aspect has also been considered using ANSYS. Modal analysis has been compared in vacuum and lead bismuth eutectic using the calculated added mass.

Natural Frequency Shift in a Centrifugal Compressor Impeller for High-Density Gas Applications

2011 ◽  
Author(s):  
Yohei Magara ◽  
Kazuyuki Yamaguchi ◽  
Haruo Miura ◽  
Naohiko Takahashi ◽  
Mitsuhiro Narita
Keyword(s):  
Centrifugal Compressor ◽  
Natural Frequencies ◽  
Mass Density ◽  
Mass Effect ◽  
Added Mass ◽  
High Density ◽  
Experimental Results ◽  
Centrifugal Compressors ◽  
Resonance Frequencies ◽  
Discharge Gas

In designing an impeller for centrifugal compressors, it is important to predict the natural frequencies accurately in order to avoid resonance caused by pressure fluctuations due to rotorstator interaction. However, the natural frequencies of an impeller change under high-density fluid conditions. The natural frequencies of pump impellers are lower in water than in air because of the added mass effect of water, and in high-pressure compressors the mass density of the discharge gas can be about one-third that of water. So to predict the natural frequencies of centrifugal compressor impellers, the influence of the gas must be considered. We previously found in the non-rotating case that some natural frequencies of an impeller decreased under high-density gas conditions but others increased and that the increase of natural frequencies is caused by fluid-structure interaction, not only the added mass effect but also effect of the stiffness of the gas. In order to develop a method for predicting natural frequencies of centrifugal compressor impellers for high-density gas applications, this paper presents experimental results obtained using a variable-speed centrifugal compressor with vaned diffusers. The maximum mass density of its discharge gas is approximately 300 kg/m3. The vibration stress on an impeller when the compressor was speeding up or slowing down was measured by strain gages, and the natural frequencies were determined by resonance frequencies. The results indicate that for high-density centrifugal compressors, some natural frequencies of an impeller increased in high-density gas. To predict this behavior, we developed a calculation method based on the theoretical analysis of a rotating disc. Its predictions are in good agreement with experimental results.

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