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This paper aims to give an extended analytical solution for the thermal evolution of rotating tubes irradiated by a Gaussian laser beam. The heating process of opaque targets by surface absorption of laser radiation is a topic of fundamental importance in many civilian and military applications (e.g. hollow tube processing, counter of rockets, mortars and artillery shells). The spatio-temporal distribution of the temperature is analytically determined by the heat equation. Explicit solutions of this parabolic partial differential equation only exist for specific cases such as flat surfaces and specific beam profiles.

In this paper, the author derives an explicit function that allows the calculation of the spatio-temporal temperature for the case of a tube irradiated by a laser beam. For this purpose, the tube geometry is transformed on that of an infinite extended slab. The heat source is transformed by the method of images to be periodically placed on the slab. Furthermore, the derived formula concerns even a rotation of the tube around the longitudinal axis.

From the calculations, the strong decrease in maximum temperatures and the spatio-temporal modulation could quantitatively be shown. For high rotation speeds, the modulation shows a falling tendency and the temperature approaches an asymptotic evolution. For this spatio-temporal evolution, the author found also an analytical expression allowing a relatively easy and fast calculation formula.

The analytical solutions were used for further calculations concerning the thermal ignition of encased explosives in rotating tubes. With the help of the formulas, the ignition times over a broad parameter range were determined.

This numerical study explores the influence of the time dependence of material fluid parameters on the transient temperature evolution during the growth of fluid shells. The shell is spherical, the fluid is Newtonian, and the flow is induced by a constant driving pressure. The coupled heat and flow equations are solved numerically using the cobody (Lagrangian) transformation and a central difference discretization in space. The range of material values is adjusted from existing experiments. It is generally found that the variation in viscosity, surface tension and specific heat can have a significant influence on both the growth rate and temperature evolution. Thermal conductivity is found to be of little influence.

To present numerical approaches to the solution of physically coupled non‐linear problems, which frequently happen to be characterized by their multi‐domain character.

By adopting coupled solution strategies a considerable attention is devoted, in order to obtain a computationally efficient numerical algorithm, to the selection of appropriate space and time discretization, as well as to a proper discrete approximation method used.

Coupling of two methods, the finite element method and the boundary element method, respectively, has proved to be computationally exceedingly advantageous, particularly in case of moving domains.

As specific case studies computer simulation of an induction heating problem and a mushy‐state forming problem are considered. A thorough discussion on the coupling effects, characterizing the evolutions of respective physical quantities' fields, is given, and their impact on those evolutions is identified.

This paper presents efficient numerical strategies for the solution of a certain class of multi‐physics and multi‐domain problems.

Metal additive manufacturing is an inherently thermal process, with intense localised heating and for sparse lattice structures, often rapid uneven cooling. Thermal effects influence manufactured geometry through residual stresses and may also result in non-isotropic material properties. This paper aims to increase understanding of the evolution of the temperature field during fabrication of lattice structures through numerical simulation.

This paper uses a reduced order numerical analysis based on “best-practice” compromise found in literature to explore design permutations for lattice structures and provide first-order insight into the effect of these design variables on the temperature field.

Instantaneous and peak temperatures are examined to discover trends at select lattice locations. Insights include the presence of vertical struts reduces overall lattice temperatures by providing additional heat transfer paths; at a given layer, the lower surface of an inclined strut experiences higher temperatures than the upper surface throughout the fabrication of the lattice; during fabrication of the lower layers of the lattice, isolated regions of material can experience significantly higher temperatures than adjacent regions.

Due to the simplifying assumptions and multi-layer material additions, the findings are qualitative in nature. Future research should incorporate additional heat transfer mechanisms.

These findings point towards thermal differences within the lattice which may manifest as dimensional differences and microstructural changes in the built part.

The paper provides qualitative insights into the effect of local geometry and topology upon the evolution of temperature within lattice structures fabricated in metal additive manufacturing.

Additive manufacturing (AM) is revolutionizing the manufacturing industry due to several advantages and capabilities, including use of rapid prototyping, fabrication of complex geometries, reduction of product development cycles and minimization of material waste. As metal AM becomes increasingly popular for aerospace and defense original equipment manufacturers (OEMs), a major barrier that remains is rapid qualification of components. Several potential defects (such as porosity, residual stress and microstructural inhomogeneity) occur during layer-by-layer processing. Current methods to qualify AM parts heavily rely on experimental testing, which is economically inefficient and technically insufficient to comprehensively evaluate components. Approaches for high fidelity qualification of AM parts are necessary.

This review summarizes the existing powder-based fusion computational models and their feasibility in AM processes through discrete aspects, including process and microstructure modeling.

Current progresses and challenges in high fidelity modeling of AM processes are presented.

Potential opportunities are discussed toward high-level assurance of AM component quality through a comprehensive computational tool.

The thermal behavior at the interfaces (of the deposited strands) during fused filament fabrication (FFF) technique strongly influences bond formation and it is a time- and temperature-dependent process. The processing parameters affect the thermal behavior at the interfaces and the purpose of the paper is to simulate using temperature-dependent (nonlinear) thermal properties rather than constant properties.

Nonlinear temperature-dependent thermal properties are used to simulate the FFF process in a simulation software. The finite-element model is first established by comparing the simulation results with that of analytical and experimental results of acrylonitrile butadiene styrene and polylactic acid. Strand temperature and time duration to reach critical sintering temperature for the bond formation are estimated for one of the deposition sequences.

Temperatures are estimated at an interface and are then compared with the experimental results, which shows a close match. The results of the average time duration (time to reach the critical sintering temperature) of strands with the defined deposition sequences show that the first interface has the highest average time duration. Varying processing parameters show that higher temperatures of the extruder and envelope along with higher extruder diameter and lower convective heat transfer coefficient will have more time available for bonding between the strands.

A novel numerical model is developed using temperature-dependent (nonlinear) thermal properties to simulate FFF processes. The model estimates the temperature evolution at the strand interfaces. It helps to evaluate the time duration to reach critical sintering temperature (temperature above which the bond formation occurs) as it cools from extrusion temperature.

A numerical study is carried out to investigate the influence of multistage drying regimes on the drying kinematics of a porous material. In particular the effects of varying the conditions of the drying medium are studied. The drying model for the solid is developed based on the continuum approach. A series of simulations of the drying behaviour of a rectangular brick with varying temperature, heat transfer coefficient and relative humidity of the drying medium are undertaken. It is found that the total drying time is mainly dependent on the relative humidity of the drying medium. Also condensation is predicted on the surface of the brick, with the quantity of condensation being directly linked to the relative humidity and temperature of the drying medium. Overall it is concluded that multistage drying regimes are useful in reducing the overall drying time whilst avoiding detrimental shrinkage during the constant drying period.

The purpose of this paper is to focus on applications related to the hyperthermia treatment of cancer, with heating imposed either by a laser in the near-infrared range or by radiofrequency waves. The particle filter algorithms are compared in terms of computational time and solution accuracy.

The authors extend the analyses performed in their previous works to compare three different algorithms of the particle filter, as applied to the hyperthermia treatment of cancer. The particle filters examined here are the sampling importance resampling (SIR) algorithm, the auxiliary sampling importance resampling (ASIR) algorithm and Liu & West’s algorithm.

Liu & West’s algorithm resulted in the largest computational times. On the other hand, this filter was shown to be capable of dealing with very large uncertainties. In fact, besides the uncertainties in the model parameters, Gaussian noises, similar to those used for the SIR and ASIR filters, were added to the evolution models for the application of Liu & West’s filter. For the three filters, the estimated temperatures were in excellent agreement with the exact ones.

This work may help medical doctors in the future to prescribe treatment protocols and also opens the possibility of devising control strategies for the hyperthermia treatment of cancer.

The natural solution to couple the uncertain results from numerical simulations with the measurements that contain uncertainties, aiming at the better prediction of the temperature field of the tissues inside the body, is to formulate the problem in terms of state estimation, as performed in this work.

This paper aims to deal with numerical modelling of composite panels of naval industry exposed to fire. Finite element (FE) analyses have been used to study the thermomechanical behaviour of structures. This paper focuses more particularly on assumptions used to model and evaluate design performance of sandwich panels made of E-Glass vinyl ester and balsawood cored submitted to a certification fire test.

The methodology consisted of having an advanced understanding of phenomena occurring in both thermal and mechanical behaviours when large structures are degraded under thermal solicitation. Then, properties measuring methods were explored and studied in relation with the size of the structure they are used to describe. Finally, several modelling strategies were compared and applied to large-size panels under ISO 834 fire conditions.

Research studies and comparisons showed that for these types of material and these types of structure, non-linear thermomechanical behaviour can be performed with a so-called “reduced” thermal model, provided that properties are measured in an appropriate way. “Reduced” model was compared with “full” model, and results were close to experimental measures. A mechanical properties’ review allowed selecting only necessary material FE analysis of large panels under ISO 834 fire.

The research was conducted on real-size structures taking into account the real conditions in which structures are tested when passing certification. Work was carried out on reducing numerical model size without neglecting phenomenon or losing accuracy.

The purpose of this paper is to model the convective flows in a room equipped by a glass door and a heated floor of length l = 0.8 × H and submitted to a sinusoidal temperature profile and mono alternative temperature profile.

The paper opts for a numerical study of convective flows in a large scale cavity using the Lattice Boltzmann Method (LBM) by considering a two dimensions (2D) square cavity of side H and filled by air (Pr = 0.71). All the vertical walls, the ceiling and the rest of the floor are thermally insulated, the hot portion of length l = 0.8×H is heated with two imposed temperature profiles of amplitude values 0.2 ≤  a  ≤ 0.6 and for two different periods ζ = ζ0 and ζ = 0.4×ζ0. One of the vertical walls has a cold portion θ_c = 0 that represents the glass door.

A systematic study of the flow structure and heat transfer is carried out considering principal control parameters: amplitude “a” and period ζ for Rayleigh number Ra = 10⁸. Effects of these parameters on results are presented in terms of isotherms, streamlines, profiles of velocities, temperature in the cavity, global and local Nusselt number. It has been found that an increase in amplitude or period increases the amplitude of the temperature in the core of cavity. The Nusselt number increases when the amplitude “a” of the imposed temperature increases, but this later is not affected by variation of the period.

The authors used LBM to simulate the convective flows in a cavity at high Ra, heated from below by tow imposed temperature profiles. Indeed, they simulate a local equipped by a solar water heater (SWH). The floor is subjected to a periodic heating: Sinusoidal heating (Case 1) for which the temperature varies sinusoidally (SWH without a supplement), and mono alternation heating (Case 2), the temperature evolves like a redressed signal (SWH with a supplement). The considered method has been successfully validated and compared with the previous work. The study has been conducted using several control parameters such as the signal amplitude and period in the case of turbulent convection. This allowed us to obtain a considerable set of results that can be used for engineering.