Continuum Model for Ion Gating in Cochlear Hair Cells

1997 ◽  
Vol 50 (11S) ◽  
pp. S210-S215
Author(s):  
Charles R. Steele
Keyword(s):  
Flow Rate ◽  
Continuum Model ◽  
Mechanical Response ◽  
Elastic Interaction ◽  
Physical Parameters ◽  
Cochlear Hair Cells ◽  
Ion Flow ◽  
Basic Fluid ◽  
Spring Force ◽  
Flow Through

The details of ion flow in cells are important for the macro mechanical response of sensory organs, as in the inner ear of vertebrates. A continuum model for the flow of an ionized fluid through a pore in an elastic wall is considered. With this, the electro-mechanical behavior is readily computed. An interesting result is that two equilibria exist for the flow through a pore with a soft elastic entrance region. At one equilibrium point, the entrance opening is more restricted and the corresponding ion flow rate is much lower. Thus it appears that the tendency of ion channels to pop from an open to a closed state may be a consequence of basic fluid-elastic interaction. With the simple continuum model, various effects can be explored. One is the presence of an external spring force, corresponding to the force of the tip fiber between stereocilia. Another is the effect of an adjacent membrane and pore. The input physical parameters are reasonable and the results for flow rate are consistent with experimental measurements.

Study of fluid flow through a channel deformed by piezoelement

2018 ◽  
Vol 13 (3) ◽  
pp. 1-10 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh Nasibullaeva ◽  
O.V. Darintsev
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Contact Surface ◽  
Piezoelectric Element ◽  
Neumann Boundary ◽  
Differential Pressure ◽  
Physical Parameters ◽  
Flow Through

The flow of a liquid through a tube deformed by a piezoelectric cell under a harmonic law is studied in this paper. Linear deformations are compared for the Dirichlet and Neumann boundary conditions on the contact surface of the tube and piezoelectric element. The flow of fluid through a deformed channel for two flow regimes is investigated: in a tube with one closed end due to deformation of the tube; for a tube with two open ends due to deformation of the tube and the differential pressure applied to the channel. The flow rate of the liquid is calculated as a function of the frequency of the deformations, the pressure drop and the physical parameters of the liquid.

Stabilization of the Speed of the Hydraulic Motor Through Throttle Compensation for Volume Losses

2020 ◽  
Vol 26 (3) ◽  
pp. 126-130
Author(s):  
Krasimir Kalev
Keyword(s):  
Flow Rate ◽  
Hydraulic Drive ◽  
Pressure Change ◽  
Operating Conditions ◽  
Drive System ◽  
Inlet Pressure ◽  
Schematic Diagram ◽  
Hydraulic Characteristics ◽  
Hydraulic Motor ◽  
Flow Through

AbstractA schematic diagram of a hydraulic drive system is provided to stabilize the speed of the working body by compensating for volumetric losses in the hydraulic motor. The diagram shows the inclusion of an originally developed self-adjusting choke whose flow rate in the inlet pressure change range tends to reverse - with increasing pressure the flow through it decreases. Dependent on the hydraulic characteristics of the hydraulic motor and the specific operating conditions.

scholarly journals Numerical simulation of periodic MHD casson nanofluid flow through porous stretching sheet

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Abdullah Al-Mamun ◽  
S. M. Arifuzzaman ◽  
Sk. Reza-E-Rabbi ◽  
Umme Sara Alam ◽  
Saiful Islam ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Lewis Number ◽  
Stability And Convergence ◽  
Radiation Absorption ◽  
Physical Parameters ◽  
Theoretical Idea ◽  
Prostate Cancer Therapy ◽  
Flow Through ◽  
Explicit Finite Difference ◽  
The Stability

AbstractThe perspective of this paper is to characterize a Casson type of Non-Newtonian fluid flow through heat as well as mass conduction towards a stretching surface with thermophoresis and radiation absorption impacts in association with periodic hydromagnetic effect. Here heat absorption is also integrated with the heat absorbing parameter. A time dependent fundamental set of equations, i.e. momentum, energy and concentration have been established to discuss the fluid flow system. Explicit finite difference technique is occupied here by executing a procedure in Compaq Visual Fortran 6.6a to elucidate the mathematical model of liquid flow. The stability and convergence inspection has been accomplished. It has observed that the present work converged at, Pr ≥ 0.447 indicates the value of Prandtl number and Le ≥ 0.163 indicates the value of Lewis number. Impact of useful physical parameters has been illustrated graphically on various flow fields. It has inspected that the periodic magnetic field has helped to increase the interaction of the nanoparticles in the velocity field significantly. The field has been depicted in a vibrating form which is also done newly in this work. Subsequently, the Lorentz force has also represented a great impact in the updated visualization (streamlines and isotherms) of the flow field. The respective fields appeared with more wave for the larger values of magnetic parameter. These results help to visualize a theoretical idea of the effect of modern electromagnetic induction use in industry instead of traditional energy sources. Moreover, it has a great application in lung and prostate cancer therapy.

Influence of surface stress on the mechanical response of nanoporous metals studied by an atomistically informed continuum model

2021 ◽  
pp. 117373
Author(s):  
Arne J. Klomp ◽  
Alexander Stukowski ◽  
Ralf Müller ◽  
Karsten Albe ◽  
Felix Diewald
Keyword(s):  
Surface Stress ◽  
Continuum Model ◽  
Mechanical Response ◽  
Nanoporous Metals

scholarly journals A continuum model for meltwater flow through compacting snow

2017 ◽  
Vol 11 (6) ◽  
pp. 2799-2813 ◽  
Author(s):  
Colin R. Meyer ◽  
Ian J. Hewitt
Keyword(s):  
Continuum Model ◽  
Pore Space ◽  
Water Storage ◽  
Greenland Ice Sheet ◽  
Percolation Process ◽  
Surface Mass ◽  
Run Off ◽  
Flow Through ◽  
Energy Balances ◽  
Mass And Energy Balances

Abstract. Meltwater is produced on the surface of glaciers and ice sheets when the seasonal energy forcing warms the snow to its melting temperature. This meltwater percolates into the snow and subsequently runs off laterally in streams, is stored as liquid water, or refreezes, thus warming the subsurface through the release of latent heat. We present a continuum model for the percolation process that includes heat conduction, meltwater percolation and refreezing, as well as mechanical compaction. The model is forced by surface mass and energy balances, and the percolation process is described using Darcy's law, allowing for both partially and fully saturated pore space. Water is allowed to run off from the surface if the snow is fully saturated. The model outputs include the temperature, density, and water-content profiles and the surface runoff and water storage. We compare the propagation of freezing fronts that occur in the model to observations from the Greenland Ice Sheet. We show that the model applies to both accumulation and ablation areas and allows for a transition between the two as the surface energy forcing varies. The largest average firn temperatures occur at intermediate values of the surface forcing when perennial water storage is predicted.

Modeling of the Ionized Fluid Flow through a Cone-Shaped Nanopore

2007 ◽  
Vol 121-123 ◽  
pp. 1089-1092 ◽  
Author(s):  
Jian Zhong Fu ◽  
Xiao Bing Mi ◽  
Yong He ◽  
Zi Chen Chen
Keyword(s):  
Fluid Flow ◽  
Theoretical Analysis ◽  
Cross Section ◽  
Debye Length ◽  
Velocity Profiles ◽  
Gradual Change ◽  
Ion Flow ◽  
Flow Through

Theoretical analysis of the ionized fluid flowing through a cone-shaped nanopore is presented. The internal cross section of the cone-shaped channel is in the range from micro- to nanometer and gradual change from larger to smaller than the Debye length for the ions. The model is developed to predict the ionized fluid flow behaviors in cone-shaped micro/nanochannels. The velocity profiles of ion flow that occur in nanopores are obtained.

scholarly journals Computational Fluid Dynamic Accuracy in Mimicking Changes in Blood Hemodynamics in Patients with Acute Type IIIb Aortic Dissection Treated with TEVAR

2018 ◽  
Vol 8 (8) ◽  
pp. 1309 ◽  
Author(s):  
Andrzej Polanczyk ◽  
Aleksandra Piechota-Polanczyk ◽  
Christoph Domenig ◽  
Josif Nanobachvili ◽  
Ihor Huk ◽  
...  
Keyword(s):  
Blood Flow ◽  
Aortic Dissection ◽  
Flow Rate ◽  
Fluid Dynamic ◽  
3D Models ◽  
Renal Arteries ◽  
Acute Type ◽  
Type Iiib ◽  
Doppler Data ◽  
Flow Through

Background: We aimed to verify the accuracy of the Computational Fluid Dynamics (CFD) algorithm for blood flow reconstruction for type IIIb aortic dissection (TBAD) before and after thoracic endovascular aortic repair (TEVAR). Methods: We made 3D models of the aorta and its branches using pre- and post-operative CT data from five patients treated for TBAD. The CFD technique was used to quantify the displacement forces acting on the aortic wall in the areas of endograft, mass flow rate/velocity and wall shear stress (WSS). Calculated results were verified with ultrasonography (USG-Doppler) data. Results: CFD results indicated that the TEVAR procedure caused a 7-fold improvement in overall blood flow through the aorta (p = 0.0001), which is in line with USG-Doppler data. A comparison of CFD results and USG-Doppler data indicated no significant change in blood flow through the analysed arteries. CFD also showed a significant increase in flow rate for thoracic trunk and renal arteries, which was in accordance with USG-Doppler data (accuracy 90% and 99.9%). Moreover, we observed a significant decrease in WSS values within the whole aorta after TEVAR compared to pre-TEVAR (1.34 ± 0.20 Pa vs. 3.80 ± 0.59 Pa, respectively, p = 0.0001). This decrease was shown by a significant reduction in WSS and WSS contours in the thoracic aorta (from 3.10 ± 0.27 Pa to 1.34 ± 0.11Pa, p = 0.043) and renal arteries (from 4.40 ± 0.25 Pa to 1.50 ± 0.22 Pa p = 0.043). Conclusions: Post-operative remodelling of the aorta after TEVAR for TBAD improved hemodynamic patterns reflected by flow, velocity and WSS with an accuracy of 99%.

scholarly journals Thermal Characteristics Analysis on Multi- Heat Pipe Induced Heat Exchanger

2019 ◽  
Vol 9 (2S2) ◽  
pp. 143-147 ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cold Water ◽  
Hot Water ◽  
Working Fluid ◽  
Physical Parameters

In this investigation of multi heat pipe induced in heat exchanger shows the developments in heat transfer is to improve the efficiency of heat exchangers. Water is used as a heat transfer fluid and acetone is used as a working fluid. Rotameter is set to measure the flow rate of cold water and hot water. To maintain the parameter as experimental setup. Then set the mass flow rate of hot water as 40 LPH, 60LPH, 80 LPH, 100LPH, 120 LPH and mass flow rate of cold water as 20 LPH, 30 LPH, 40 LPH, 50 LPH, and 60 LPH. Then 40 C, 45 ºC, 50 ºC, 55 C, 60 ºC are the temperatures of hot water at inlet are maintained. To find some various physical parameters of Qc , hc , Re ,, Pr , Rth. The maximum effectiveness of the investigation obtained from condition of Thi 60 C, Tci 32 C and 100 LPH mhi, 60 LPH mci the maximum effectiveness attained as 57.25. Then the mhi as 100 LPH, mci as 60 LPH and Thi at 40 C as 37.6%. It shows the effectiveness get increased about 34.3 to the maximum conditions.

Influence of an inclined magnetic field on the Poiseuille flow of immiscible micropolar–Newtonian fluids in a porous medium

2018 ◽  
Vol 96 (9) ◽  
pp. 1016-1028 ◽  
Author(s):  
Pramod Kumar Yadav ◽  
Sneha Jaiswal
Keyword(s):  
Magnetic Field ◽  
Rotational Velocity ◽  
Immiscible Fluids ◽  
Newtonian Fluids ◽  
Porous Channel ◽  
Physical Parameters ◽  
Inclined Magnetic Field ◽  
Two Phase ◽  
Flow Through ◽  
Newtonian Viscous Fluid

The present problem is concerned with two-phase fluid flow through a horizontal porous channel in the presence of uniform inclined magnetic field. The micropolar fluid or Eringen fluid and Newtonian viscous fluid are flowing in the upper and lower regions of the horizontal porous channel, respectively. In this paper, the permeability of each region of the horizontal porous channel has been taken to be different. The effects of various physical parameters like angles of inclination of magnetic field, viscosity ratio, micropolarity parameter, etc., on the velocities, micro-rotational velocity of two immiscible fluids in horizontal porous channel, wall-shear stress, and flow rate have been discussed. The result obtained for immiscible micropolar–Newtonian fluids are compared with the results of two immiscible Newtonian fluids. The obtained result may be used in production of oil from oil reservoirs, purification of contaminated ground water, etc.

Experimental, Numerical, and Statistical Investigation of Two Phase Flow in a Cylindrical Perforation Tunnel

2021 ◽  
Author(s):  
Ekhwaiter Abobaker ◽  
Abadelhalim Elsanoose ◽  
Mohammad Azizur Rahman ◽  
Faisal Khan ◽  
Amer Aborig ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Statistical Analysis ◽  
Flow Rate ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Gas Flow Rate ◽  
Two Phase ◽  
Flow Through

Abstract Perforation is the final stage in well completion that helps to connect reservoir formations to wellbores during hydrocarbon production. The drilling perforation technique maximizes the reservoir productivity index by minimizing damage. This can be best accomplished by attaining a better understanding of fluid flows that occur in the near-wellbore region during oil and gas operations. The present work aims to enhance oil recovery by modelling a two-phase flow through the near-wellbore region, thereby expanding industry knowledge about well performance. An experimental procedure was conducted to investigate the behavior of two-phase flow through a cylindrical perforation tunnel. Statistical analysis was coupled with numerical simulation to expand the investigation of fluid flow in the near-wellbore region that cannot be obtained experimentally. The statistical analysis investigated the effect of several parameters, including the liquid and gas flow rate, liquid viscosity, permeability, and porosity, on the injection build-up pressure and the time needed to reach a steady-state flow condition. Design-Expert® Design of Experiments (DoE) software was used to determine the numerical simulation runs using the ANOVA analysis with a Box-Behnken Design (BBD) model and ANSYS-FLUENT was used to analyses the numerical simulation of the porous media tunnel by applying the volume of fluid method (VOF). The experimental data were validated to the numerical results, and the comparison of results was in good agreement. The numerical and statistical analysis demonstrated each investigated parameter’s effect. The permeability, flow rate, and viscosity of the liquid significantly affect the injection pressure build-up profile, and porosity and gas flow rate substantially affect the time required to attain steady-state conditions. In addition, two correlations obtained from the statistical analysis can be used to predict the injection build-up pressure and the required time to reach steady state for different scenarios. This work will contribute to the clarification and understanding of the behavior of multiphase flow in the near-wellbore region.

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