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High‐power chemical lasers operating in high repetitive rate show a decrease of the output energy laser beam. In such lasers, the characteristic time which depends on the laser output is short in comparison with those related to the flow. Consequently, shock waves, acoustic waves and thermal perturbations, induced by the strong electric energy deposition and remaining in the laser cavity between two pulses, may explain the decrease of output energy of the laser beam. For a better understanding of the flowfields, a numerical approach is carried out using flux corrected transport algorithms (FCT methods) associated with a Riemann solver on the computational domain boundaries. Under two‐dimensional assumptions, the inviscid flow in the convergent‐divergent laser cavity is computed to describe the creation and propagation of the wave system and the hot gas column in both single and multidischarge operating modes. Distortions of the contact surfaces are put into evidence through the study of flowfield instabilities. Finally, the limitations of the two‐dimensional modelization become apparent. The numerical resolution is extended to a 3D case in order to take into account the optical direction. This allows to study the influence of shock waves travelling between optics and being generated by a side effect developing at the electrodes. These waves have an effect of long duration on the flowfield and lead to a high residual perturbation level.

The aim of this paper is to develop and validate a model and a numerical code describing the laser matter interaction and also laser ablation. The laser wavelength is 193 nm and the pulse duration is several nanoseconds.

The developed model is based on strong theoretical background (cf. references). The electronic nonequilibrium aspect is always taken into account. The electronic nonequilibrium is one of the key aspect the UV laser matter interaction and must be treated carefully and that is not always the case. The numerical code was developed using efficient and versatile numerical methods. The model and simulations are always compared to experiments in order to validate them and also to find their limitations.

This work has greatly improved the code accuracy. The key role of the electronic nonequilibrium is also demonstrated. From experimental comparisons it is obvious that photo‐ablation should be taken into account for the lower fluences, but to do so, a completely new approach must be developed.

This work describes the whole laser ablation process with the electronic nonequilibrium effects properly modeled. The numerical results has always been confronted to experiments, in most of the cases the agreement was very good. When it was not the case, explanations have been sought along with ways to improve the approach.

The aim is to study the effects of fin conductivity ratio, Darcy number, and Rayleigh number on the average Nusselt number for fins made of porous material when attached to the inner cylinder of the annulus between two concentric cylinders. The paper also aims to compare the results with those obtained using solid fins over a range of Rayleigh numbers.

The Darcy‐Brinkman equations were used to model the fluid flow inside the porous media and the Boussinesq approximation was used to model the buoyancy effect. The energy equation is also solved to find the temperature distribution in the domain of interest. The model equations are solved numerically using a finite volume code.

Porous fins provided higher heat transfer rates than solid fins for similar configurations. This enhancement in heat transfer reached 75 per cent at Ra=5 × 10⁴ and Da=2.5 × 10⁻². It is also found that unlike solid fins the rate of heat transfer from the cylinder equipped with porous fins decreases with increasing the fin inclination angle.

The range of the Rayleigh number considered in this research covers only the laminar regime. The research does not cover turbulent flows. In addition to that, the local thermal equilibrium assumption is used.

This work can help designers in selecting the proper material properties and operating conditions in designing porous fins to enhance the heat transfer in the annulus between two horizontal concentric cylinders under natural convection condition.

This work has not been done before and it can initiate additional research projects as looking at the performance of porous fins under other conditions and configurations (e.g. turbulent conditions).

Non‐equilibrium hypersonic viscous flows with high enthalpy conditions have been computed with an implicit time‐dependent finite‐difference scheme. This scheme accounts for both chemical and vibrational non‐equilibrium processes in air flow around a hemispherical cylindrical body. The air was assumed to decompose into the following five species N, O, NO, N₂ and O₂ and only the two diatomic species N₂ and O₂ are taken in thermal non‐equilibrium. A range of Mach number from 14 to 18 has been investigated. The numerical results have been compared with those obtained by other workers and are in agreement with ballistic range data concerning the standoff shock distance at M = 15.3. The computed heat flux wall follows the trends of the experiments with an under prediction increasing with the Mach number. The influence of the thermal non‐equilibrium assumption on the computed standoff shock distance is investigated.

To compute the Navier‐Stokes equations of a non‐equilibrium weakly ionized air flow. This can help to have a better description of the flow‐field and the wall heat transfer in hypersonic conditions.

The numerical approach is based on a multi block finite volume method and using a Riemann's solver based on a MUSCL‐TVD algorithm. In the flux splitting procedure the modified speed of sound, due to the electronic mode, is implemented.

A good description of the shock standoff distance, of the wall heat fluxes and of the peak of electron density number in the shock layer.

The radiative effects are not included in this paper. For the very high Mach numbers, this can modify the shock layer parameters.

The knowledge of the wall heat transfer in the re‐entry body problems.

The building of a robust numerical code in order to well describe hypersonic air flow in high Mach numbers.

How can a manager lead an organization or a team in a particularly turbulent time? How can management cope with chaos and uncertainty? Drawing on behavioral strategy theory, this study aims at investigating how hubristic managers can enable organizations to thrive, even over small time periods, in chaotic and uncertain contexts and settings.

This study uses a qualitative methodology to explore the possible positive effects of hubris in a behavioral strategy. In particular, 45 interviews with leaders and followers of particularly high-performing secondary schools have been administered to try to fully understand the origin, process and performance evolution of organizations led by hubristic managers.

The results showed that, in chaotic and uncertain times, hubris can prove to be a trump card for managers in dealing with the pitfalls and uncertainties of the context in which the organization operates. Three major attributes were identified – overconfidence and over-persistence, recklessness and contempt for critical feedback – defining the positive behavioral strategies implemented by hubristic managers during the COVID-19 pandemic.

To the best of the authors’ knowledge, this study is the first to highlight, by means of qualitative methodologies, the positive managerial hubristic-behavioral strategy during turbulent times in the school sector.

The Fay and Riddell (F–R) formula is an empirical equation for estimating the stagnation-point heat flux on noncatalytic and fully catalytic surfaces, based on an assumption of equilibrium. Because of its simplicity, the F–R has been used extensively for reentry flight design as well as ground test facility applications. This study aims to investigate the uncertainties of the F-R formula by considering velocity gradient, chemical species at the boundary layer edge, and the thermochemical nonequilibrium (NEQ) behind the shock layer under various hypersonic NEQ flow environments.

The stagnation-point heat flux calculated with the F–R formula was evaluated by comparison with thermochemical NEQ calculations and existing flight experimental values.

The comparisons showed that the F–R underestimated the noncatalytic heat flux, because of the chemical composition at the surface. However, for fully catalytic heat flux, the F–R results were similar to values of surface heat flux from thermochemical NEQ calculations, because the F–R formula overestimates the diffusive heat flux. When compared with the surface heat flux results obtained from flight experimental data, the F–R overestimated the fully catalytic heat flux. The error was 50% at most.

The results provided guidelines for the F–R calculations under hypersonic flight conditions and for determining the approximate error range for noncatalytic and fully catalytic surfaces.

A numerical simulation of a two‐phase dilute flow (droplet‐gas mixture) is carried out by using a finite volume method based on Riemann solvers. The computational domain represents a one‐ended pipe with holes at its upper wall which lead into an enclosure. The aim of this study is to determine the parameters of such a flow. More specially, an analytical solution is compared with numerical results to assess the mass flow rates through the vents in the pipe. Inertia effects dominate the dynamic behaviour of droplets, which causes a non‐homogeneous flow in the cavity. The unsteady effects are also important, which makes isentropical calculation irrelevant and shows the necessity of the use of CFD tools to predict such flows. No relation can be extracted from the numerical results between the gas and the dispersed mass flow rates across the holes. But a linear variation law for the droplet mass flow versus the position of the holes is pointed out, which is independent of the incoming flow when the evaporating effects are quite low.

There is growing interest in how hubris bias shapes managerial and entrepreneurial judgments and decisions and, in turn, firm strategy and performance. Based on a 44-years dataset of articles reaching the beginning of 2023, the authors offer a synthesis of hubris research published within business journals.

The authors implement a mixed-method approach offering a content representation of 600 peer-reviewed articles extracted from Scopus. The authors conduct a bibliometric investigation – employing Excel, VOSViewer and Biblioshiny software – and perform a qualitative review.

The analysis unveils four thematic clusters: hubris bias in financial policies (Cluster 1), hubris bias in restructuring deals (Cluster 2), hubris bias in entrepreneurial contexts (Cluster 3) and hubris bias in strategic decision-making (Cluster 4). Moreover, the authors infer that hubris research in business predominantly developed from three disciplinary perspectives – finance, entrepreneurship and strategic management – and progressed with limited interdisciplinary dialogue.

The authors call practitioners' attention to the impact of the hubris bias in forming financial, entrepreneurial and strategic choices. Managers get conscious of the risks of hubristic choices; hence, they implement organizational practices that move forward with unbiased (or less biased) judgments and decisions.

The authors offer an up-to-date and comprehensive view of hubris research in business. Furthermore, the authors provide an integrative framework and a research agenda.

This paper aims to describe the physical and numerical modeling of a new computational fluid dynamics solver for hypersonic flows in thermo-chemical non-equilibrium. The code uses a blend of numerical techniques to ensure accuracy and robustness and to provide scalability for advanced hypersonic physics and complex three-dimensional (3D) flows.

The solver is based on an edge-based stabilized finite element method (FEM). The chemical and thermal non-equilibrium systems are loosely-coupled to provide flexibility and ease of implementation. Chemical non-equilibrium is modeled using a laminar finite-rate chemical kinetics model while a two-temperature model is used to account for thermodynamic non-equilibrium. The systems are solved implicitly in time to relax numerical stiffness. Investigations are performed on various canonical hypersonic geometries in two-dimensional and 3D.

The comparisons with numerical and experimental results demonstrate the suitability of the code for hypersonic non-equilibrium flows. Although convergence is shown to suffer to some extent from the loosely-coupled implementation, trading a fully-coupled system for a number of smaller ones improves computational time. Furthermore, the specialized numerical discretization offers a great deal of flexibility in the implementation of numerical flux functions and boundary conditions.

The FEM is often disregarded in hypersonics. This paper demonstrates that this method can be used successfully for these types of flows. The present findings will be built upon in a later paper to demonstrate the powerful numerical ability of this type of solver, particularly with respect to robustness on highly stretched unstructured anisotropic grids.