Search results

By modeling and analyzing the two-phase mechanical seal of the fan-shaped groove end face, which is prone to phase change, an effective method to study the flow field of the mechanical seal when both cavitation and boiling exist simultaneously is found.

Based on the finite volume method, a fluid model was developed to investigate a two-phase mechanical seal. The validity of the proposed model was verified by comparing with some classical models.

By modeling and analyzing the two-phase mechanical seal of the fan-shaped groove end face, which is prone to phase change, the analysis of the gap flow field of the mechanical seal was realized when cavitation and boiling existed simultaneously.

Based on the model proposed for different conditions, the pressure and phase states in the shallow groove sealing gap were compared. The phase change rate between the mechanical seal faces was also investigated.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0537/

Cyclic phase change involves the successive freezing and melting of a region driven by a boundary temperature that cycles above and below the solid/liquid phase change temperature. In this paper, a recently proposed fixed grid phase change enthalpy method is modified and applied to cyclic solid/liquid phase change problems. The basic approach is demonstrated on application to a one‐dimensional, heat conduction controlled phase change. Then the method is used to investigate a cyclic phase change problem that involves fluid flow. The interaction of the melting and freezing with the phase change leads to some interesting predictions for the location and shape of the solid/liquid interface. The results also indicate that melting cycles are more effective than freezing cycles.

This paper develops an argument about how contentious changes unfold in organizational fields, focusing on the role of uncertainty – and the networks people use to address uncertainty. We propose that as controversial practice gains traction and spreads, the nature of uncertainty facing organizational decision makers also evolves. This dynamic has important implications for how different actors and networks can influence change. We illustrate our argument with a mixed-methods case study on the diffusion of domestic partner benefits across US Fortune 500 companies. Our findings shed light on how – and when – social activists, corporate elites, and middle managers can influence the corporate decision-making process.

Organisational decline has far-reaching, negative emotional and financial consequences for staff and customers, generating academic and practitioner interest in turnaround change processes. Despite numerous studies to identify the stages during turnarounds, the findings have been inconclusive. The purpose of this paper is to address the gap by defining these stages, or episodes. The characteristics of leaders affect the outcome of organisational change towards turnarounds. This paper focusses, therefore, on the leadership requirements during specific episodes, from the initial crisis to the full recovery phases.

A total of 11 semi-structured interviews were conducted with executives from the public sector in South Africa who went through or were going through turnaround change processes and 3 with experts consulting to these organisations.

Contrary to current literature in organisational change, this study found that, in these turnaround situations, leadership in the form of either an individual CEO or director general was preferable to shared leadership or leadership distributed throughout the organisation. This study found four critical episodes that occurred during all the public service turnarounds explored, and established that key leadership requirements differ across these episodes. The study shows how these requirements relate to the current literature on transactional, transformational and authentic leadership.

The findings on the leadership requirements ultimately inform the selection and development of leaders tasked with high-risk turnaround change processes.

Four episodes with corresponding leadership requirements were established in the particular context of public sector turnaround change processes.

Kubler‐Ross′ stages of death and dying – denial, anger, bargaining, depression and acceptance‐have formed the basis of much of the therapeutic work with the terminally ill. As death and dying are the ultimate instances of change in a person′s life, it is hypothesised that Kubler‐Ross′ work has an application to the theory and process of change. A four‐stage model of organisational change‐denying, dodging, doing and sustaining – based on Kubler‐Ross is presented. These four stages are linked to the four organisational levels, generating a seven‐phase framework that integrates the complex interplay of denying, dodging, doing and sustaining in the individual, the team, the group and the organisation.

A method has been developed for conjugate heat transfer analysis of fluid flow inside parallel channels formed by a phase change material (PCM) separated from the fluid by a wall. The phase change in the PCM is two dimensional and a hybrid analysis consisting of an analytical solution in one direction and a finite‐difference method in another direction is used to solve for the temperature in the PCM. The heat transfer fluid (HTF) inlet temperature is given and the heat transfer between the HTF and the PCM is treated as a conjugate problem that requires no iterations to obtain a solution. The numerical results are found to be stable, convergent, and accurate. Application of the method to the solution of heat extraction from a phase‐change energy storage unit is given in detail and the numerical results are shown to be accurate, based on an energy conservation analysis, to within 3%.

Describes research into managers′ experiences of significant organizational change attempts. The research project was aimed at developing frameworks which: describe, illuminate and enable a better understanding of managers′ journeys through organizational change; serve as a template for bringing together the very diverse and fragmented literature relating to individuals experiencing change; highlight issues and pointers for the design and facilitation of effective organizational change initiatives. The first part describes the context, spirit, intentions, sample and methodology of the research. Also, reviews a broad range of literature which can inform our understanding of individuals in change. Propounds the need to open up the “real world” of organizational change, as perceived and experienced by managers, rather than any “ideal” view of how that world is desired or supposed to be. Presents and discusses research findings on the sensed and initiating “primary” triggers for change‐that is, the formal and communicated organizational change objectives; and the perceived and felt “secondary” triggers for change‐that is, the issues raised by, and the implications of, the organizational changes for individual managers. The second part presents a framework depicting the phases and components of managers′ journeys through organizational change. On the framework, the experience of managers can be located, in terms of their thoughts, feelings and behaviours, as the processes of change unfold. While each manager′s journey was found to be unique, the framework proved to be ubiquitous in enabling the mapping of all the managers′ journeys, and it also accommodates literature on phenomena as diverse as learning, personal transition, catastrophe and survival, trauma and stress, loss and “death”, and worry and grief. The findings emphasize the profoundness and deeply felt emotionality of many managers′ experiencing of change in organizations. Finally, identifies the outcomes of managers′ journeys through significant attempts at organizational change. Also presents the reported helping and hindering factors to those journeys. Implications of these findings are pursued, particularly in terms of the leadership and development roles and behaviours required, if the organization and its management are to move beyond simply requiring change towards actively facilitating its achievement.

The purpose of this paper is to develop a coupled lattice Boltzmann model for the simulation of the freezing process in unsaturated porous media.

In the developed model, the porous structure with complexity and disorder was generated by using a stochastic growth method, and then the Shan-Chen multiphase model and enthalpy-based phase change model were coupled by introducing a freezing interface force to describe the variation of phase interface. The pore size of porous media in freezing process was considered as an influential factor to phase transition temperature, and the variation of the interfacial force formed with phase change on the interface was described.

The larger porosity (0.2 and 0.8) will enlarge the unfrozen area from 42 mm to 70 mm, and the rest space of porous medium was occupied by the solid particles. The larger specific surface area (0.168 and 0.315) has a more fluctuated volume fraction distribution.

The concept of interfacial force was first introduced in the solid–liquid phase transition to describe the freezing process of frozen soil, enabling the formulation of a distribution equation based on enthalpy to depict the changes in the water film. The increased interfacial force serves to diminish ice formation and effectively absorb air during the freezing process. A greater surface area enhances the ability to counteract liquid migration.

The present paper describes the applicability of hybrid transfinite element modelling/analysis formulations for non‐linear heat conduction problems involving phase change. The methodology is based on application of transform approaches and classical Galerkin schemes with finite element formulations to maintain the modelling versatility and numerical features for computational analysis. In addition, in conjunction with the above, the effects due to latent heat are modelled using enthalpy formulations to enable a physically realistic approximation to be effectively dealt computationally for materials exhibiting phase change within a narrow band of temperatures. Pertinent details of the approach and computational scheme adapted are described in technical detail. Numerical test cases of comparative nature are presented to demonstrate the applicability of the proposed formulations for numerical modelling/analysis of non‐linear heat conduction problems involving phase change.

A phase‐change temperature‐based formulation including general latent heat effects is presented. These effects are taken into account by means of an explicit “phase‐change function” (or liquid fraction‐temperature relationship in a more specific context) defined analytically or based on experimental measurements. The behaviour of different functions is studied and compared. The finite element equations of this formulation are also described. Finally, a numerical example is analysed to illustrate the performance of the proposed methodology.