Numerical investigations on bubble-induced jetting and shock wave focusing: application on a needle-free injection

The formation of a liquid jet into air induced by the growth of a laser-generated bubble inside a needle-free device is numerically investigated by employing the compressible Navier–Stokes equations. The three co-existing phases (liquid, vapour and air) are assumed to be in thermal equilibrium. A transport equation for the gas mass fraction is solved in order to simulate the non-condensable gas. The homogeneous equilibrium model is used in order to account for the phase change process between liquid and vapour. Thermodynamic closure for all three phases is achieved by a barotropic Equation of State. Two-dimensional axisymmetric simulations are performed for a needle-free device for which experimental data are available and used for the validation of the developed model. The influence of the initial bubble pressure and the meniscus geometry on the jet velocity is examined by two different sets of studies. Based on the latter, a new meniscus design similar to shaped-charge jets is proposed, which offers a more focused and higher velocity jet compared to the conventional shape of the hemispherical gas–liquid interface. Preliminary calculations show that the developed jet can penetrate the skin and thus, such configurations can contribute towards a new needle-free design

The causal ordering of key cross-functional relationship dimensions: a replication study using the marketing/R&D relationship.

How do working relationships between functional managers develop, and how are they maintained? Does interpersonal trust drive communication, or is communication the building block of interpersonal trust? Massey and Dawes (2002) examined the causal ordering of three key behavioural constructs - communication behaviours, interpersonal trust, and interpersonal conflict in cross-functional relationships between Marketing Managers and Sales Managers. By using three competing models they found evidence that CFRs are built on a foundation of effective communication, specifically, bidirectional communication. This current paper is a replication of their study in the context of the Marketing/R&D relationship during 184 Australian new product development projects. It contributes to the literature, by corroborating the causal ordering suggested by Massey and Dawes (2002). These findings have significant implications for the selection of strategies by senior management to better integrate the Marketing and R&D functions

An empirical test of the information processing and socio-political perspectives in new product development projects

New product development research draws on a range of different theories, though no overarching theory explaining NPD success has emerged. Atuahene-Gima and Evangelista (2000) however identified an underlying dichotomy in existing theories: economically rational approaches, and socio-political approaches. In this paper we test a model which reflects this dichotomy, and using data from 184 NPD projects, we provide empirical evidence that that this multi-lens theoretical approach has great potential to better understand factors driving NPD outcomes

The effects of organisational structure, interpersonal trust and communication during new product development projects

This study examines the antecedents of effective working relationships between Marketing and R&D managers during NPD projects. Adopting both a structural and individual-level perspective, we examine the impact on relationship effectiveness of formalisation, centralisation, communication frequency and bidirectionality, and interpersonal trust between Marketing Managers and R&D Managers during NPD product development projects. Our hypothesised model is tested using a sample of 184 product development projects conducted in Australia, and our findings reveal two dimensions of interpersonal trust (cognition- and affect-based trust) are potent factors driving effectiveness during product development projects. We also reveal differential effects of the two communication behaviours, and demonstrate that unlike bidirectional communication, communication frequency does not increase relationship effectiveness. Similarly, whilst formalisation can help improve relationship effectiveness on product development projects, centralisation does not have any positive effect

Communication and conflict between marketing and R&D during new product development projects

Effective cross-functional working relationships (CFRs) between Marketing Managers and R&D Managers are a key factor in successful new product development (NPD). Empirical evidence suggests however, that this CFR is often problematic. This article adds to our knowledge about Marketing/R&D CFRs during NPD by examining the effects of three forms of communication (communication frequency, bidirectionality, and quality) on two forms of conflict (dysfunctional and functional conflict). A hypothesised model of Marketing/R&D CFRs is tested using a sample of 184 NPD projects conducted in Australia, using R&D Managers as key respondents reporting on their relationships with the relevant Marketing Manager. Our findings reveal that communication quality and bidirectional communication, have strong effects on both forms of conflict. Also, the managerial use of frequent communication is ineffective in reducing dysfunctional conflict during NPD projects

Interpersonal trust between marketing and R&D during new product development projects

Purpose - The primary objective of this research is to test a model examining interpersonal trust between marketing managers and R&D managers during new product development projects. Design/methodology/approach - In this study interpersonal trust as a bi-dimensional construct with cognitive and affective components is conceptualised. The authors' integrative structural model specifies Weber's structural/bureaucratic dimensions - formalisation and centralisation to predict three communication dimensions, communication frequency, quality, and bi-directionality. In turn these communication dimensions are used to predict cognition-based trust, and affect-based trust. In addition, the paper models the direct effects of the three communication dimensions on a dependent variable - perceived relationship effectiveness. The hypothesised model consists of 16 hypotheses, seven of which relate to the two focal interpersonal trust constructs. The measures were tested and a structural model estimated by using PLS. Data were provided by 184 R&D managers in Australia, reporting on their working relationship with a counterpart marketing manager during a recent product development project. Findings - The hypothesized model has high explanatory power and it was found that both trust dimensions strongly influenced the effectiveness of marketing/R&D relationships during new product development, with cognition-based trust having the strongest impact. The results also reveal which forms of communication help to build interpersonal trust. The most powerful effect was from communication quality to cognition-based trust. The next strongest effects were from bi-directional communication, which was a strong predictor of affect-based trust, and a somewhat weaker predictor of cognition-based trust. Interestingly, the direct effects of our three communication behaviours on relationship effectiveness were modest, suggesting that their relationship building effects are largely indirect. Last, it is revealed that bureaucratic means of control on product development projects have mixed effects. As expected, centralisation reduces cross-functional communication. In contrast, formalisation has a positive effect during product development, as it stimulates both the frequency and bi-directionality of communication between marketing managers and R&D managers on these projects. Originality/value - This is the first study to treat interpersonal trust as the focal construct in marketing/R&D relationships during new product development. Moreover, it is the only study of marketing/R&D relationships to conceptualise, measure, and model two underlying dimensions of interpersonal trust (cognition-based trust, and affect-based trust). Our study also integrates aspects of Weber's theory of bureaucracy, with interaction theory, and demonstrates the strong links between these theoretical frameworks. © Emerald Group Publishing Limited

Cavitation Induction by Projectile Impacting on a Water Jet

The present paper focuses on the simulation of the high-velocity impact of a projectile impacting on a water-jet, causing the onset, development and collapse of cavitation. The simulation of the fluid motion is carried out using an explicit, compressible, density-based solver developed by the authors using the OpenFOAM library. It employs a barotropic two-phase flow model that simulates the phase-change due to cavitation and considers the co-existence of non-condensable and immiscible air. The projectile is considered to be rigid while its motion through the computational domain is modelled through a direct-forcing Immersed Boundary Method. Model validation is performed against the experiments of Field et al. [Field, J., Camus, J. J., Tinguely, M., Obreschkow, D., Farhat, M., 2012. Cavitation in impacted drops and jets and the effect on erosion damage thresholds. Wear 290–291, 154–160. doi:10.1016/j.wear.2012.03.006. URL http://www.sciencedirect.com/science/article/pii/S0043164812000968 ], who visualised cavity formation and shock propagation in liquid impacts at high velocities. Simulations unveil the shock structures and capture the high-speed jetting forming at the impact location, in addition to the subsequent cavitation induction and vapour formation due to refraction waves. Moreover, model predictions provide quantitative information and a better insight on the flow physics that has not been identified from the reported experimental data, such as shock-wave propagation, vapour formation quantity and induced pressures. Furthermore, evidence of the Richtmyer-Meshkov instability developing on the liquid-air interface are predicted when sufficient dense grid resolution is utilised

Social Housing as a State-Funded Mega Project: A Case Study From Saudi Arabia

There are many kinds of war. They span from typical military conflicts to socially and politically charged environments, from fiscal colonization to ghostly wars about information and the internet. But what about the fear of a possible war? Could housing initiatives be connected to that? What kind of design methods and standards as well as processes would that specific case entail? What other factors would add pressure to studying and implementing housing projects in this context? What could be the possible measure of such projects’ eventual assessment? This paper is based on the assumption that fear of a spreading of the Arab Spring in the Saudi Kingdom triggered a massive state-funded housing project. The ambitious case of Saudi Arabia’s Ministry of Housing (MoH) will be discussed and gradually unfolded within its social, cultural, economic, and technical-design conditions. The project’s development is discussed both before its launch-conceptualization and throughout its implementation. The original insight given stems from the authors’ participation as lead urban planners in one of the major companies awarded the project

Modelling cavitation during drop impact on solid surfaces

The impact of liquid droplets on solid surfaces at conditions inducing cavitation inside their volume has rarely been addressed in the literature. A review is conducted on relevant studies, aiming to highlight the differences from non-cavitating impact cases. Focus is placed on the numerical models suitable for the simulation of droplet impact at such conditions. Further insight is given from the development of a purpose-built compressible two-phase flow solver that incorporates a phase-change model suitable for cavitation formation and collapse; thermodynamic closure is based on a barotropic Equation of State (EoS) representing the density and speed of sound of the co-existing liquid, gas and vapour phases as well as liquid-vapour mixture. To overcome the known problem of spurious oscillations occurring at the phase boundaries due to the rapid change in the acoustic impedance, a new hybrid numerical flux discretization scheme is proposed, based on approximate Riemann solvers; this is found to offer numerical stability and has allowed for simulations of cavitation formation during drop impact to be presented for the first time. Following a thorough justification of the validity of the model assumptions adopted for the cases of interest, numerical simulations are firstly compared against the Riemann problem, for which the exact solution has been derived for two materials with the same velocity and pressure fields. The model is validated against the single experimental data set available in the literature for a 2-D planar drop impact case. The results are found in good agreement against these data that depict the evolution of both the shock wave generated upon impact and the rarefaction waves, which are also captured reasonably well. Moreover, the location of cavitation formation inside the drop and the areas of possible erosion sites that may develop on the solid surface, are also well captured by the model. Following model validation, numerical experiments have examined the effect of impact conditions on the process, utilizing both planar and 2-D axisymmetric simulations. It is found that the absence of air between the drop and the wall at the initial configuration can generate cavitation regimes closer to the wall surface, which significantly increase the pressures induced on the solid wall surface, even for much lower impact velocities. A summary highlighting the open questions still remaining on the subject is given at the end