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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.

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.

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.

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

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.

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.

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

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.

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.

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

The purpose of this study is to investigate the impact of the oscillatory movement on heat transfer within a double periodic lid-driven cubic enclosure filled with copper-water nanofluid and to figure out how the oscillations impact the fluid flow and thermal behavior inside the enclosure. The authors asserted that this study will help to improve the heat transfer efficiency and the thermal performance of various technical engineering equipments.

The cubic enclosure is heated differentially; the left side is cold, the right one is warm and the remaining walls are insulated. Based on the movement directions of the upper and bottom lids, two cases for lid-driven walls are examined (Case 1: same movement for both lids; Case 2: opposite movement for the lids). The finite volume approach was implemented to solve the time-dependent three-dimensional momentum and energy equations, adopting the power low as a scheme of resolution. The numerical study was carried out for a range of parameters: volume fraction (0 ≤ φ ≤ 0.06), Richardson number (0.1 ≤ Ri ≤ 10), non-dimensional lid frequency (2π/50 ≤ Ω ≤ 2π/10) and fixed Grashof number 105.

The numerical simulations were executed for two different cases of the direction of the motion of the oscillatory lids. Based on the findings obtained, decreasing the Richardson number with low lids frequency gives the best heat transfer enhancement for both cases. Furthermore, in the same conditions, swapping from Case 2 to Case 1 leads to enhancing the maximum average Nusselt number obtained by 29.74%. At a high Richardson number, using high lids frequency increases the heat transfer rate compared to using low lids frequency (an enhancement of 4.32% for Case 1 and 3.63% for Case 2). The best heat transfer rate was established for Case 1 when the lids move positively, transporting the cold flow to the hot side. In all cases, increasing the concentration of nanoparticles improves the heat transfer.

The current study gives an understanding of the problem of mixed convection in a cubic enclosure with oscillatory walls, which has received little attention. And also, there has been no study published on unsteady mixed convection within a double oscillatory lid-driven cavity.

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.

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.

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)/[6η_bulk(1−ξ)(u_a+u_b)]); 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.

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.

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.

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.

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

This paper aims to study the impact of transient velocity changes on sealing performance during reciprocating sealing processes.

Establish a model of transient mixed lubrication, solve the transient Reynolds equation, consider the effect of temperature rise at the seal interfaces, and determine the behavior of the seal interfaces, such as film thickness and fluid pressure. Evaluation with friction and leakage rate, calculate the variation of sealing performance with reciprocating velocity under different working conditions, and verify it through bench experiments.

Within a reciprocating stroke, the frictional force decreases with increasing velocity, and the frictional force of the outstroke is greater than that of the instroke; at the time of the stroke transition, the fluid pressure is smallest and the rough peak contact pressure is greatest. At present, the dynamic pressure effect of fluids is the largest, and the friction force also increases, which increases the risk of material wear and failure. Friction and leakage increase with increasing pressure and root mean square roughness. As temperature increases, friction increases and leakage decreases. In studying the performance variations of seal components through a reciprocating sealing experiment, it was found that the friction force decreases with increasing velocity, which is consistent with the calculated results and more similar to the calculated results considering the temperature rise.

This study provides a reference for the study of transient sealing performance.

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

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).

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.

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