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Article
Publication date: 1 October 1963

I.M. Hall

THE development of undergraduate teaching in Aeronautical Engineering at Manchester University has followed a different pattern from that in most other Universities in…

Abstract

THE development of undergraduate teaching in Aeronautical Engineering at Manchester University has followed a different pattern from that in most other Universities in this country. Although Osborne Reynolds carried out his famous experiments in the Engineering Department at Manchester, the teaching of Aeronautical Engineering grew out of Mathematics rather than out of Engineering. For a large proportion of the past 80 years the Chair of Applied Mathematics has been held by men eminent in the field of Fluid Mechanics: Lamb, Goldstein and Lighthill must surely be names well‐known to every aeronautical engineer. It was due to the initiative of Professor S. Goldstein that a separate Department of Fluid Mechanics was set up in 1946 under the direction of Mr W. A. Mair. At first it was natural that the emphasis should be on experimental work to complement the theoretical work carried out in the Mathematics Department. Later, however, although close relations with the Mathematics Department were still maintained, the Mechanics of Fluids Department developed into a separate entity making both theoretical and experimental contributions to fundamental knowledge.

Details

Aircraft Engineering and Aerospace Technology, vol. 35 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 27 March 2008

P. Nithiarasu

This paper aims to present briefly a unified fractional step method for fluid dynamics, incompressible solid mechanics and heat transfer calculations. The proposed method…

Abstract

Purpose

This paper aims to present briefly a unified fractional step method for fluid dynamics, incompressible solid mechanics and heat transfer calculations. The proposed method is demonstrated by solving compressible and incompressible flows, solid mechanics and conjugate heat transfer problems.

Design/methodology/approach

The finite element method is used for the spatial discretization of the equations. The fluid dynamics algorithm used is often referred to as the characteristic‐based split scheme.

Findings

The proposed method can be employed as a unified approach to fluid dynamics, heat transfer and solid mechanics problems.

Originality/value

The idea of using a unified approach to fluid dynamics and incompressible solid mechanics problems is proposed. The proposed approach will be valuable in complicated engineering problems such as fluid‐structure interaction and problems involving conjugate heat transfer and thermal stresses.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 1 February 1961

G. Pallett

Fluid mechanics is essentially an experimental subject, and similarity laws in one form or another are its natural background. Various types of similarity are possible: in…

Abstract

Fluid mechanics is essentially an experimental subject, and similarity laws in one form or another are its natural background. Various types of similarity are possible: in the first place there is geometric similarity between the model and the prototype. If the ratio of any two corresponding dimensions in the two systems is a constant then there is geometric similarity. The ratio is called the scale ratio. At this stage it is worth pointing out that complete similarity, even in the geometric sense, is not often possible. Such factors as surface roughness or particle size may be very difficult to match. In the case of, say, river models practical considera‐tions necessitate separate vertical and horizontal scales.

Details

Education + Training, vol. 3 no. 2
Type: Research Article
ISSN: 0040-0912

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Article
Publication date: 19 May 2021

Hua-Lin Yang, Xiulong Li, Weiwei Sun, Fang Deng and Jie Du

This paper aims to present the mixed elastohydrodynamic lubrication (EHL) model and obtain the leakage characteristics for the skeleton reciprocating oil seal.

Abstract

Purpose

This paper aims to present the mixed elastohydrodynamic lubrication (EHL) model and obtain the leakage characteristics for the skeleton reciprocating oil seal.

Design/methodology/approach

The model consists of a finite element analysis of the contact pressure, a fluid mechanics analysis of the fluid film, a contact analysis of the asperity contact pressure, a deformation analysis of the seal lip and an iterative numerical simulation process.

Findings

Simulation results show that the leakage is in direct proportion to the seal roughness and speed, and in inverse proportion to the fluid viscosity. Comparisons with the experimental results verify the validity of the mixed EHL model.

Originality/value

This study provides a helpful method to calculate the leakage of the skeleton reciprocating oil seal, which shortens its development cycles.

Details

Industrial Lubrication and Tribology, vol. 73 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 May 2006

Y. Zhang

To develop a more realistic model for molecularly thin film hydrodynamic lubrication by incorporating the fluid inhomogeneity and discontinuity effects across the fluid

Abstract

Purpose

To develop a more realistic model for molecularly thin film hydrodynamic lubrication by incorporating the fluid inhomogeneity and discontinuity effects across the fluid film thickness in this lubrication.

Design/methodology/approach

The total mass flow of the fluid through the contact in a basic one‐dimensional molecularly thin film hydrodynamic lubrication is studied by incorporating the fluid inhomogeneity and discontinuity effects across the fluid film thickness, based on a simplified momentum transfer model between neighboring fluid molecules across the fluid film thickness. This flow is calculated according to the present approach and the theory of viscous flow between two contact surfaces. The total mass flow of the fluid through the contact in this lubrication is also calculated from conventional hydrodynamic lubrication theory, which was based on continuum fluid assumption in the whole lubricated contact. The ratio of this flow calculated from the present approach to that calculated from conventional hydrodynamic lubrication theory is here defined as the flow factor for a one‐dimensional molecularly thin film hydrodynamic lubrication due to the fluid inhomogeneity and discontinuity effects. Results of this flow factor are presented for wide operational parameters.

Findings

In the molecularly thin film hydrodynamic lubrication, when the fluid inhomogeneity and discontinuity across the fluid film thickness both are incorporated, the total fluid mass flow through the contact and thus the global fluid film thickness are increased. The combined effect of the fluid inhomogeneity and discontinuity across the fluid film thickness on the total fluid mass flow through the contact in this lubrication is determined by the operational parameter K=((∂p/∂xh2)/[6ηbulk(1−ξ)(ua+ub)]); when the operational parameter K is high, this effect is significant; when the operational parameter K is low, this effect is negligible. On the other hand, in this lubrication, when the combined effect of the fluid inhomogeneity and discontinuity across the fluid film thickness is incorporated, the shear stresses at the contact‐fluid interfaces are reduced and this reduction can be significant. This reduction may strongly depend on the value of the dimensionless discontinuity parameter Δ/D of the fluid across the fluid film thickness but weakly depend on the number n of the fluid molecules across the fluid film thickness.

Practical implications

An important and very useful research for the academic researcher and the engineer who are, respectively, engaged in the study and design of hydrodynamic lubrication on mechanical components especially of very low hydrodynamic lubrication film thickness. It is also important to the subsequent research of molecularly thin film hydrodynamic lubrication.

Originality/value

A new model of molecularly thin film hydrodynamic lubrication in one‐dimensional contacts is originally proposed and described by incorporating the fluid inhomogeneity and discontinuity effects across the fluid film thickness in this lubrication. This new model of molecularly thin film hydrodynamic lubrication is of importance to the theoretical study of molecularly thin film hydrodynamic lubrication.

Details

Industrial Lubrication and Tribology, vol. 58 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 November 2003

Rama Subba Reddy Gorla and Nagasekhar Reddy Gorla

Fluid flow in a circular pipe and a slider bearing was computationally simulated by finite element methods and probabilistically evaluated in view of the several…

Abstract

Fluid flow in a circular pipe and a slider bearing was computationally simulated by finite element methods and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for the flow rate and load bearing capacity of the slider bearing due to the several random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in fluid flow and to the identification of both the most critical measurements and parameters.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 13 no. 7
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 August 1934

M.A. Tenot

THE Mechanics Laboratory of the Arts et Métiers School of Châlons‐sur‐Marne fulfils a threefold object:—

Abstract

THE Mechanics Laboratory of the Arts et Métiers School of Châlons‐sur‐Marne fulfils a threefold object:—

Details

Aircraft Engineering and Aerospace Technology, vol. 6 no. 8
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 6 November 2017

Luca Marioni, Mehdi Khalloufi, Francois Bay and Elie Hachem

This paper aims to develop a robust set of advanced numerical tools to simulate multiphase flows under the superimposition of external uniform magnetic fields.

Abstract

Purpose

This paper aims to develop a robust set of advanced numerical tools to simulate multiphase flows under the superimposition of external uniform magnetic fields.

Design/methodology/approach

The flow has been simulated in a fully Eulerian framework by a {\it variational multi-scale} method, which allows to take into account the small-scale turbulence without explicitly model it. The multi-fluid problem has been solved through the convectively re-initialized level-set method to robustly deal with high density and viscosity ratio between the phases and the surface tension has been modelled implicitly in the level-set framework. The interaction with the magnetic field has been modelled through the classic induction equation for 2D problems and the time step computation is based on the electromagnetic interaction to guarantee convergence of the method. Anisotropic mesh adaptation is then used to adapt the mesh to the main problem’s variables and to reach good accuracy with a small number of degrees of freedom. Finally, the variational multiscale method leads to a natural stabilization of the finite elements algorithm, preventing numerical spurious oscillations in the solution of Navier–Stokes equations (fluid mechanics) and the transport equation (level-set convection).

Findings

The methodology has been validated, and it is shown to produce accurate results also with a low number of degrees of freedom. The physical effect of the external magnetic field on the multiphase flow has been analysed.

Originality/value

The dam-break benchmark case has been extended to include magnetically constrained flows.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 11
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 28 April 2014

Seth Dillard, James Buchholz, Sarah Vigmostad, Hyunggun Kim and H.S. Udaykumar

The performance of three frequently used level set-based segmentation methods is examined for the purpose of defining features and boundary conditions for image-based…

Abstract

Purpose

The performance of three frequently used level set-based segmentation methods is examined for the purpose of defining features and boundary conditions for image-based Eulerian fluid and solid mechanics models. The focus of the evaluation is to identify an approach that produces the best geometric representation from a computational fluid/solid modeling point of view. In particular, extraction of geometries from a wide variety of imaging modalities and noise intensities, to supply to an immersed boundary approach, is targeted.

Design/methodology/approach

Two- and three-dimensional images, acquired from optical, X-ray CT, and ultrasound imaging modalities, are segmented with active contours, k-means, and adaptive clustering methods. Segmentation contours are converted to level sets and smoothed as necessary for use in fluid/solid simulations. Results produced by the three approaches are compared visually and with contrast ratio, signal-to-noise ratio, and contrast-to-noise ratio measures.

Findings

While the active contours method possesses built-in smoothing and regularization and produces continuous contours, the clustering methods (k-means and adaptive clustering) produce discrete (pixelated) contours that require smoothing using speckle-reducing anisotropic diffusion (SRAD). Thus, for images with high contrast and low to moderate noise, active contours are generally preferable. However, adaptive clustering is found to be far superior to the other two methods for images possessing high levels of noise and global intensity variations, due to its more sophisticated use of local pixel/voxel intensity statistics.

Originality/value

It is often difficult to know a priori which segmentation will perform best for a given image type, particularly when geometric modeling is the ultimate goal. This work offers insight to the algorithm selection process, as well as outlining a practical framework for generating useful geometric surfaces in an Eulerian setting.

Details

Engineering Computations, vol. 31 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 26 August 2014

Immanuvel Paul, K. Arul Prakash and S. Vengadesan

The purpose of this paper is to study the effects of Angle of Attack (AOA), Axis Ratio (AR) and Reynolds number (Re) on unsteady laminar flow over a stationary elliptic…

Abstract

Purpose

The purpose of this paper is to study the effects of Angle of Attack (AOA), Axis Ratio (AR) and Reynolds number (Re) on unsteady laminar flow over a stationary elliptic cylinder.

Design/methodology/approach

The governing equations of fluid flow over the elliptic cylinder are solved numerically on a Cartesian grid using Projection method based Immersed Boundary technique. This numerical method is validated with the results available in open literature. This scheme eliminates the requirement of generating a new computational mesh upon varying any geometrical parameter such as AR or AOA, and thus reduces the computational time and cost.

Findings

Different vortex shedding patterns behind the elliptic cylinder are identified and classified using time averaged centerline streamwise velocity profile, instantaneous vorticity contours and instantaneous streamline patterns. A parameter space graph is constructed in order to reveal the dependence of AR, AOA and Re on vortex shedding. Integral parameters of flow such as mean drag, mean lift coefficients and Strouhal number are calculated and the effect of AR, AOA and Re on them is studied using various pressure and streamline contours. Functional relationships of each of integral parameters with respect to AR, AOA and Re are proposed with minimum percentage error.

Practical implications

The results obtained can be used to explain the characteristics of flow patterns behind slender to bluff elliptical cylinders which found applications in insect flight modeling, heat exchangers and energy conservation systems. The proposed functional relationships may be very useful for the practicing engineers in those fields.

Originality/value

The results presented in this paper are important for the researchers in the area of bluff body flow. The dependence of AOA on vortex shedding and flow parameters was never reported in the literature. These results are original, new and important.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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