• Coupled systems mechanics
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• v.9 no.3
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• pp.289-309
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• 2020

The paper studies the fluid flow profile contained between the orthotropic plate and rigid wall under the action of the moving load on the plate and main attention is focused on the fluid velocity profile in the load moving direction. It is assumed that the plate material is orthotropic one and the fluid is viscous and barotropic compressible. The plane-strain state in the plate and the plane flow of the fluid is considered. The motion of the plate is described by utilizing the exact equations of elastodynamics for anisotropic bodies, however, the flow of the fluid by utilizing the linearized Navier-Stokes equations. For the solution of the corresponding boundary value problem, the moving coordinate system associated with the moving load is introduced, after which the exponential Fourier transformation is employed with respect to the coordinate which indicates the distance of the material points from the moving load. The exact analytical expressions for the Fourier transforms of the sought values are obtained, the originals of which are determined numerically. Presented numerical results and their analyses are focused on the question of how the moving load acting on the face plane of the plate which is not in the contact with the fluid can cause the fluid flow and what type profile has this flow along the thickness direction of the strip filled by the fluid and, finally, how this profile changes ahead and behind with the distance of the moving load.

• Wind and Structures
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• v.39 no.1
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• pp.31-45
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• 2024

This paper examines the flow characteristics around an inclined prism with a U-shaped cross-section ("U-profile") and investigates the connection between the flow and flow-induced vibrations. The study employs a combined approach that involves wind tunnel experiments and computational fluid dynamics (CFD) using an unsteady Reynolds-averaged Navier-Stokes (RANS) turbulence model. Distinct vortex formation patterns are observed in the flow field surrounding the stationary inclined profile. When the cavity of the profile faces away from the incoming flow, large vortices develop behind the profile. Conversely, when the cavity is oriented towards the oncoming flow, these vortices form within the cavity. Notably, due to the slow movement of these large vortices through the cavity, the frequency at which vortices are shed in the negative inclination case is lower compared to the positive inclination, where they form in the wake. Wind tunnel experiments reveal an intermittent transition between the two vortex formation patterns at zero inclination. Large vortices sporadically emerge both in the cavity and behind the profile. The simulation results demonstrate that when these large vortices occur at a frequency close to the structure's natural frequency, they induce prominent pitch vibrations. This phenomenon is also sought after and presented in coupled vibration experiments. Additionally, the simulations indicate that when the natural frequency of the structure is considerably lower than the vortex shedding frequency, this type of vibration can be observed.

• Water Engineering Research
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• v.3 no.3
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• pp.155-162
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• 2002

This study presents the theoretical approach for volume concentration, velocity profile, and granular discharge on the fluid-granule mixed flow downstream of the scour hole at the outlet of the hydraulic structure. Concept of dilatant model was applied for the stress-strain relationships of fluid-granule mixed flow since the flow downstream of the scour hole corresponds to debris flow, where momentum transfers through particle collisions. Mathematical formulations were derived using momentum equation and stress-strain relation of the fluid-granule mixture. Velocity profile under the assumption of uniform concentration over flowing layer showed the downward convex type. Deposition angle of downstream hump was found to be a function of an upstream slope angle, a dynamic friction angle and a volume concentration irrespective of flow itself, Granular discharge and the overflow depth were obtained with given values of inflow rates. Experimental results showed relatively good agreements with theoretical ones.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.449-455
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• 2009

A reversible axial flow fan called jet fan has been widely used for longitudinal ventilation in road tunnels to secure a safe and comfortable environment cost-effectively. As shifting the flow direction is usually made by only switching the rotational direction of an electric motor due to heavy duty, rotor blades having identical aerodynamic performance for bidirectional flow should be necessary. However, such aerodynamically desirable blades haven't been developed sufficiently, since most of the related studies have been done from the viewpoint of unidirectional flow. In the present paper, we demonstrate a method to profile the blade section suitable for bidirectional flow, which is validated by studying the aerodynamic performances of rotor blades of a two-stage jet fan experimentally and numerically.

• Korea-Australia Rheology Journal
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• v.17 no.4
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• pp.207-215
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• 2005

We present a finite difference solution for electrokinetic flow in rectangular microchannels encompassing Navier's fluid slip phenomena. The externally applied body force originated from between the nonlinear Poisson-Boltzmann field around the channel wall and the flow-induced electric field is employed in the equation of motion. The basic principle of net current conservation is applied in the ion transport. The effects of the slip length and the long-range repulsion upon the velocity profile are examined in conjunction with the friction factor. It is evident that the fluid slip counteracts the effect by the electric double layer and induces a larger flow rate. Particle streak imaging by fluorescent microscope and the data processing method developed ourselves are applied to straight channel designed to allow for flow visualization of dilute latex colloids underlying the condition of simple fluid. The reliability of the velocity profile determined by the flow imaging is justified by comparing with the finite difference solution. We recognized the behavior of fluid slip in velocity profiles at the hydrophobic surface of polydimethylsiloxane wall, from which the slip length was evaluated for different conditions.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.464-468
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• 2003

A general program of three dimensional profile design of impellers for centrifugal/fixed-flow compressors is successfully commercialized using Bezier curves and quasi-3D flow analysis methods. Control points for meridional hub and shroud contours and blade camberline angles are arbitrarily changed to give smooth Bezier curves. With specified blade normal thicknesses, contructed geometry is instantly analyzed using flow analysis methods to be checked.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.107-114
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• 2003

The influence of property difference in refraction index on micro PIV measurement of two-fluid flow in a microchannel was analyzed. The difference of measurement planes in two fluids would bring misunderstanding of the physics. The objective-imaging system for two-fluid flow measurement was presented, and the condition for measurement of valid velocity profile across two-fluid interface was derived. A micro PIV experimental system was set up to measure two-fluid flow inside a Y-shape microchannel. Under the conditions, three cases of two-fluid flow of glycerol solutions at different concentration (${\phi}$), e.g., (${\phi}=0\;and\;{\phi}=0.2,\;{\phi}=0.1\;and\;{\phi}=0.5,\;{\phi}=0\;and\;{\phi}=0.6$, were measured. Close agreement of experimental and numerical results was found.

• Advances in concrete construction
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• v.17 no.4
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• pp.179-185
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• 2024

Effects of MHD slip flow of second grade fluid with heat transfer are studied in the presence of heat source along permeable stretching surface. The governing boundary layer equations are complex and partial in nature. Using Lie group theory the suitable similarity transformation is derived. The system of PDEs is transformed to system of ODEs by applying these similarity transformations. The combined effect of Hartman number and porosity on velocity profile and the influence of slip parameter on fluid velocity is observed. It is found that enhancing the second grade parameter, boundary layer thickens and ultimately speedup the fluid. Also, the effect of suction/injection parameter on velocity profile is checked. An excellent agreement is noticed that assures the correctness of results. Effects of various physical parameters on the velocity and temperature profile are elaborated with graphs.

• Steel and Composite Structures
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• v.43 no.2
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• pp.221-228
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• 2022

Two-dimensional stagnation point slip flow of a Casson fluid impinging normally on a flat linearly shrinking surface is considered. The modeled PDEs are changed into nonlinear ODEs through appropriate nonlinear transformations.The flow is assumed to be steady and incompressible, with external magnetic field acting on it. Similarity transformation is utilized to investigate the behavior of many parameters for heat and velocity distributions using truncation approach.The influence of buoyancy parameter, slip parameter, shrinking parameter, Casson fluid parameter on the heat profile. The effect of the magnetic parameter on the streamwise velocity profile is also investigated.

• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.290-299
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• 2000

A three-dimensional model was developed in order to simulate heat and fluid flow of a continuous casting billet. The model was coded with the general-purpose CFD program FIDAP, using the finite element method. The present model consists of 2 individual calculation schemes, named model 1 and model 2. Mold region only was calculated to check the pouring stream through submerged nozzle with model 1. Entire region, which consists of mold, secondary cooling, radiation cooling was calculated to predict crater end position, temperature profile and solid shell profile(model 2). Standard $k-{\bullet}\hat{A}$ turbulence model has been applied to simulate the turbulent flow induced by submerged nozzle. Enthalpy method was adopted for the latent heat of solidification. Fluid flow in mushy zone was treated using variable viscosity approach. The more casting speed and superheat increased, the more metallurgical length increased. The shell thickness at the mold exit is proved to be mainly controlled by superheat by the present simulation. It may be concluded that the present model can be successfully applied far the prediction of heat and fluid flow behavior in the continuous casting process.