FLUID DYNAMICS ANALYSIS OF SHEAR STRESS ON NERVE ENDINGS IN DENTINAL MICROTUBULE: A QUANTITATIVE INTERPRETATION OF HYDRODYNAMIC THEORY FOR DENTAL PAIN

Noxious thermal and/or mechanical stimuli applied to dentine can cause fluid flow in dentinal microtubules (DMTs). The fluid flow induces shear stress (SS) on intradental nerve endings and may excite pulpal mechanoreceptors to generate dental pain sensation. There exist numerous studies on dental thermal pain, but few are mathematical. For this, we developed a computational fluid dynamics (CFD) model of dentinal fluid flow (DFF) in innervated DMTs. Based on this model, we systematically investigated the effects of various parameters (e.g., biological structure, DFF velocity, and fluid properties) on the SS experienced by intradental nerve endings and thus provide a quantitative interpretation to the hydrodynamic theory. The dimensions of biological structures, odontoblastic process (OP) movement, dentinal fluid velocity, and viscosity were found to have significant influences on the SS while dentinal fluid density showed negligible influence under conditions studied. The results indicate that: (i) dental pain study of animal models may not be directly applied to human being and the results may even vary from one person to another and (ii) OP movement caused by DFF changes the dimension of the space for the fluid flow, affecting thus the SS on nerve endings. The present work enables better understanding of the mechanisms underlying dental pain sensation and quantification of dental pain intensity resulted from clinical procedures such as dentine sensitivity testing and dental restorative processes.

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Computational Fluid Dynamics Study of the Effects of Surface Roughness on Permeability and Fluid Flow-Induced Wall Shear Stress in Scaffolds

Annals of Biomedical Engineering ◽

10.1007/s10439-018-2101-z ◽

2018 ◽

Vol 46 (12) ◽

pp. 2023-2035 ◽

Cited By ~ 8

Author(s):

Davar Ali ◽

Sadri Sen

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Surface Roughness ◽

Shear Stress ◽

Fluid Flow ◽

Wall Shear Stress ◽

Wall Shear

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Fluid-Induced Forces in Pump Liquid Seals With Large Aspect Ratio

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-06085 ◽

2011 ◽

Cited By ~ 3

Author(s):

Alexandrina Untaroiu ◽

Vahe Hayrapetian ◽

Costin D. Untaroiu ◽

Paul E. Allaire ◽

Houston G. Wood ◽

...

Keyword(s):

Shear Stress ◽

Fluid Flow ◽

Aspect Ratio ◽

Stokes Equations ◽

Complex Geometry ◽

Dynamic Properties ◽

Fluid Velocity ◽

Bulk Flow ◽

Large Aspect Ratio ◽

Aspect Ratios

The instability due to fluid flow in seals is a known phenomenon that can occur in pumps and compressors as well as in steam turbines. Traditional annular seal models are based on bulk flow theory. While these methods are computationally efficient and can predict dynamic properties fairly well for short seals, they lack accuracy in cases of seals with complex geometry or with large aspect ratios (above 1.0). Unlike the bulk flow models, computational fluid dynamics (CFD) makes no simplifying assumption on the seal geometry, shear stress at the wall, relationship between wall shear stress and mean fluid velocity, or characterization of interfaces between control volumes through empirical friction factors. This paper presents a method to calculate the linearized rotor-dynamic coefficients for a liquid seal with large aspect ratio (balance drum) subjected to incompressible turbulent flow by means of a three dimensional CFD analysis to calculate the fluid-induced forces acting on the rotor. The Reynolds-averaged Navier-Stokes equations for fluid flow are solved by dividing the volume of fluid into a discrete number of points at which unknown variables are computed. As a result, all the details of the flow field, including the fluid forces with potential destabilizing effects, are calculated. A 2nd order curve fit is then used to express the fluid-induced forces in terms of equivalent linearized stiffness, damping, and fluid inertia coefficients.

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Modelling corners flow in rectangular microchannel

Journal of Physics Conference Series ◽

10.1088/1742-6596/2119/1/012114 ◽

2021 ◽

Vol 2119 (1) ◽

pp. 012114

Author(s):

D S Gluzdov ◽

E Ya Gatapova

Keyword(s):

Shear Stress ◽

Fluid Flow ◽

Boundary Conditions ◽

Fluid Velocity ◽

Rectangular Microchannel ◽

Cross Sectional ◽

Rectangular Microchannels ◽

Lab On Chip ◽

Slip Boundary ◽

Wall Boundary Conditions

Abstract Rectangular microchannels are most common configuration in microfluidics. They can be used in many industries, for example in lab-on-chip devices. Despite standard fluid dynamics, microfluidics has a significant impact of wall boundary conditions on fluid flow. And in microfluidics, we cannot simply set no-slip boundary conditions if our goal is accurate modeling results. In rectangular microchannels, there is another important moment in modeling that is not present in circular pipes. The velocity profile of the fluid depends on the shear stress at the edges and the velocities at the walls of the microchannel change at different points of the cross-sectional wall of the microchannel. The fluid velocity is lower at the corners of a rectangular microchannel. In this paper, a solution is proposed to find a more accurate way to model the fluid flow in a rectangular microchannel by knowing the friction factor without shear stress distribution.

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Numerical study of fluid behavior on protruding shapes within the inlet part of pressurized membrane module using computational fluid dynamics

Environmental Engineering Research ◽

10.4491/eer.2018.423 ◽

2019 ◽

Vol 25 (4) ◽

pp. 498-505 ◽

Cited By ~ 1

Author(s):

Changkyoo Choi ◽

Chulmin Lee ◽

No-Suk Park ◽

In S. Kim

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Fluid Flow ◽

Numerical Study ◽

Fluid Velocity ◽

Flow Distribution ◽

Membrane Module ◽

Cross Sectional ◽

Fluid Behavior ◽

Uniform Flow Distribution

This study analyzes the velocity and pressure incurred by protruding shapes installed within the inlet part of a pressurized membrane module during operation to determine the fluid flow distribution. In this paper, to find the flow distribution within a module, it investigates the velocity and pressure values at cross-sectional and outlet planes, and 9 sections classified on outlet plane using computational fluid dynamics. From the Reynolds number (Re), the fluid flow was estimated to be turbulent when the Re exceeded 4,000. In the vertical cross-sectional plane, shape 4 and 6 (round-type protrusion) showed the relatively high velocity of 0.535 m/s and 0.558 m/s, respectively, indicating a uniform flow distribution. From the velocity and pressure at the outlet, shape 4 also displayed a relatively uniform fluid velocity and pressure, indicating that fluid from the inlet rapidly and uniformly reached the outlet, however, from detailed data of velocity, pressure and flowrate obtained from 9 sections at the outlet, shape 6 revealed the low standard deviations for each section. Therefore, shape 6 was deemed to induce the ideal flow, since it maintained a uniform pressure, velocity and flowrate distribution.

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Flow around a Triaxial Ellipsoid in a Long Circular Tube

Zeitschrift für Naturforschung A ◽

10.5560/zna.2011-0011 ◽

2011 ◽

Vol 66 (8-9) ◽

pp. 481-488

Author(s):

Doo-Sung Lee

Keyword(s):

Differential Equation ◽

Fluid Dynamics ◽

Fluid Flow ◽

Circular Cylinder ◽

Circular Tube ◽

Fluid Velocity ◽

Three Dimensional ◽

Triaxial Ellipsoid ◽

Viscous Fluid Flow ◽

Integro Differential Equation

Abstract This paper deals with the three-dimensional analysis of viscous fluid flow in a long circular cylinder containing an ellipsoidal obstacle. The center of the ellipsoid coincides with that of the cylinder, and the flow is confined to the space between the ellipsoid and the cylinder when the fluid velocity at the large distance from the ellipsoid is uniform. The equations of the classical theory of fluid dynamics are solved in terms of an unknown function which is then shown to be the solution of a boundary integro-differential equation. A numerical solution of the integro-differential equation is obtained and the pressure on the surface of the ellipsoid is presented in graphical forms for various values of the radius of the circular tube.

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Efficiency prediction for storage chambers using computational fluid dynamics

Water Science & Technology ◽

10.2166/wst.1996.0202 ◽

1996 ◽

Vol 33 (9) ◽

pp. 163-170 ◽

Cited By ~ 4

Author(s):

Virginia R. Stovin ◽

Adrian J. Saul

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Shear Stress ◽

Particle Tracking ◽

Critical Value ◽

Complex Geometries ◽

Bed Shear Stress ◽

Breadth Ratio ◽

Computational Fluid Dynamics Cfd ◽

Simulated Flow

Research was undertaken in order to identify possible methodologies for the prediction of sedimentation in storage chambers based on computational fluid dynamics (CFD). The Fluent CFD software was used to establish a numerical model of the flow field, on which further analysis was undertaken. Sedimentation was estimated from the simulated flow fields by two different methods. The first approach used the simulation to predict the bed shear stress distribution, with deposition being assumed for areas where the bed shear stress fell below a critical value (τcd). The value of τcd had previously been determined in the laboratory. Efficiency was then calculated as a function of the proportion of the chamber bed for which deposition had been predicted. The second method used the particle tracking facility in Fluent and efficiency was calculated from the proportion of particles that remained within the chamber. The results from the two techniques for efficiency are compared to data collected in a laboratory chamber. Three further simulations were then undertaken in order to investigate the influence of length to breadth ratio on chamber performance. The methodology presented here could be applied to complex geometries and full scale installations.

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The Effect of Wall Shear Stress on Two Phase Fluctuating Flow of Dusty Fluids by Using Light Hill Technique

Water ◽

10.3390/w13111587 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1587

Author(s):

Dolat Khan ◽

Ata ur Rahman ◽

Gohar Ali ◽

Poom Kumam ◽

Attapol Kaewkhao ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Base Fluid ◽

Perturbation Technique ◽

Fluid Velocity ◽

Dust Particles ◽

Stress Effect ◽

Parallel Plates ◽

Dusty Fluid ◽

Wall Shear

Due to the importance of wall shear stress effect and dust fluid in daily life fluid problems. This paper aims to discover the influence of wall shear stress on dust fluids of fluctuating flow. The flow is considered between two parallel plates that are non-conducting. Due to the transformation of heat, the fluid flow is generated. We consider every dust particle having spherical uniformly disperse in the base fluid. The perturb solution is obtained by applying the Poincare-Lighthill perturbation technique (PLPT). The fluid velocity and shear stress are discussed for the different parameters like Grashof number, magnetic parameter, radiation parameter, and dusty fluid parameter. Graphical results for fluid and dust particles are plotted through Mathcad-15. The behavior of base fluid and dusty fluid is matching for different embedded parameters.

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