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This research investigates a haptic modelling approach where high resolutions are required for sensibility of force feedback in a target application - dental surgical operations. In particular the research focus is on maxillofacial deformity operations. The main aim of the research is to increase the realism of a computer model based simulation system that allows dental students and surgeons to feel like as if they were carrying out a real dental surgery procedure. A haptic framework has been designed and implemented to demonstrate its suitability to achieve the above aim. A generic set of jaw bone models have been developed and validated by collaborating surgeon from Glasgow University Dental Hospital & School. The model can be customized and obtained for each specific patient. A chosen model can be used to control the force feedback generated by a haptic device in order to give a realistic force feedback representation and experience for a user. This meets the requirements of the targeted dental operations. The simulation model is constructed based on force calculation model, which include the consideration of mechanical properties of bones, cutting tools used and region of cut. This haptical jaw bone model has been generalised based on a contact mechanic model Hertz's equation and is used as the driving haptical model for the study. Using a haptic device as a controller, a user can perform relevant operations, such as cutting procedure and manipulating bone segments from the virtual jaw bone model. The paper describes a frame work for a haptic assisted surgical plan (HASP) for surgical planning of dentofacial deformities. The haptic system generates the corresponding force feedback to a user as in a real world operation. It is planed that validation and feedback experiments will be conducted with dental students and surgeons to assess the effectiveness of the system in providing assistance for oral and maxillofacial surgical planning and training.

Our understanding of the mechanisms of airborne transmission of viruses is incomplete. This paper employs computational multiphase fluid dynamics and heat transfer to investigate transport, dispersion, and evaporation of saliva particles arising from a human cough. An ejection process of saliva droplets in air was applied to mimic the real event of a human cough. We employ an advanced three-dimensional model based on fully coupled Eulerian–Lagrangian techniques that take into account the relative humidity, turbulent dispersion forces, droplet phase-change, evaporation, and breakup in addition to the droplet–droplet and droplet–air interactions. We computationally investigate the effect of wind speed on social distancing. For a mild human cough in air at 20 °C and 50% relative humidity, we found that human saliva-disease-carrier droplets may travel up to unexpected considerable distances depending on the wind speed. When the wind speed was approximately zero, the saliva droplets did not travel 2 m, which is within the social distancing recommendations. However, at wind speeds varying from 4 km/h to 15 km/h, we found that the saliva droplets can travel up to 6 m with a decrease in the concentration and liquid droplet size in the wind direction. Our findings imply that considering the environmental conditions, the 2 m social distance may not be sufficient. Further research is required to quantify the influence of parameters such as the environment’s relative humidity and temperature among others.

Epidemic models do not account for the effects of climate conditions on the transmission dynamics of viruses. This study presents the vital relationship between weather seasonality, airborne virus transmission, and pandemic outbreaks over a whole year. Using the data obtained from high-fidelity multi-phase, fluid dynamics simulations, we calculate the concentration rate of Coronavirus particles in contaminated saliva droplets and use it to derive a new Airborne Infection Rate (AIR) index. Combining the simplest form of an epidemiological model, the susceptible–infected–recovered, and the AIR index, we show through data evidence how weather seasonality induces two outbreaks per year, as it is observed with the COVID-19 pandemic worldwide. We present the results for the number of cases and transmission rates for three cities, New York, Paris, and Rio de Janeiro. The results suggest that two pandemic outbreaks per year are inevitable because they are directly linked to what we call weather seasonality. The pandemic outbreaks are associated with changes in temperature, relative humidity, and wind speed independently of the particular season. We propose that epidemiological models must incorporate climate effects through the AIR index.

The contribution of this paper toward understanding of airborne coronavirus survival is twofold: We develop new theoretical correlations for the unsteady evaporation of coronavirus (CoV) contaminated saliva droplets. Furthermore, we implement the new correlations in a three-dimensional multiphase Eulerian–Lagrangian computational fluid dynamics solver to study the effects of weather conditions on airborne virus transmission. The new theory introduces a thermal history kernel and provides transient Nusselt (Nu) and Sherwood (Sh) numbers as a function of the Reynolds (Re), Prandtl (Pr), and Schmidt numbers (Sc). For the first time, these new correlations take into account the mixture properties due to the concentration of CoV particles in a saliva droplet. We show that the steady-state relationships induce significant errors and must not be applied in unsteady saliva droplet evaporation. The classical theory introduces substantial deviations in Nu and Sh values when increasing the Reynolds number defined at the droplet scale. The effects of relative humidity, temperature, and wind speed on the transport and viability of CoV in a cloud of airborne saliva droplets are also examined. The results reveal that a significant reduction of virus viability occurs when both high temperature and low relative humidity occur. The droplet cloud’s traveled distance and concentration remain significant at any temperature if the relative humidity is high, which is in contradiction with what was previously believed by many epidemiologists. The above could explain the increase in CoV cases in many crowded cities around the middle of July (e.g., Delhi), where both high temperature and high relative humidity values were recorded one month earlier (during June). Moreover, it creates a crucial alert for the possibility of a second wave of the pandemic in the coming autumn and winter seasons when low temperatures and high wind speeds will increase airborne virus survival and transmission.

The variation of the liquid properties in the vicinity of a solid surface complicates the description of heat transfer along solid-liquid interfaces. Using Molecular Dynamics simulations, this investigation aims to understand how the material properties, particularly the strength of the solid-liquid interaction, affect the thermal conductivity of the liquid at the interface. The molecular model consists of liquid argon confined by two parallel, smooth, solid walls, separated by a distance of 6.58σ. We find that the component of the thermal conductivity parallel to the surface increases with the affinity of the solid and liquid.

This paper concerns the implementation of the generalized polynomial chaos (gPC) approach for parametric studies, including the quantification of uncertainty (UQ), of turbulence modelling. The method is applied to Richtmyer-Meshkov turbulent mixing. The K-L turbulence model has been chosen as a prototypical example, and parametric studies have been performed to examine the effects of closure coefficients and initial conditions on the flow results. It is shown that the proposed method can be used to obtain a relation between the uncertain inputs and the monitored flow quantities, thus efficiently performing parametric studies. It allows the simultaneous calibration and quantification of uncertainty in an efficient numerical framework.

This paper investigates the accuracy of implicit large eddy simulations (ILES) in compressible turbulent boundary layers (TBL). ILES are conducted in conjunction with Monotonic Upstream-Centred Scheme for Conservation Laws (MUSCL) and Weighted Essentially Non-Oscillatory (WENO), ranging from 2nd to 9th-order. The excess artificial dissipation occurring at low Mach numbers is counter-balanced by using low Mach corrections. The study concludes that high-order ILES provide accurate predictions of TBL even on relatively coarse grids.

The solution of the non-hydrostatic compressible Euler equations using Weighted Essentially Non-Oscillatory (WENO) schemes in two and three-dimensional unstructured meshes, is presented. Their key characteristics are their simplicity; accuracy; robustness; non-oscillatory properties; versatility in handling any type of grid topology; computational and parallel efficiency. Their defining characteristic is a non-linear combination of a series of high-order reconstruction polynomials arising from a series of reconstruction stencils. In the present study an explicit TVD Runge-Kutta 3rd -order method is employed due to its lower computational resources requirement compared to implicit type time advancement methods. The WENO schemes (up to 5th -order) are applied to the two dimensional and three dimensional test cases: a 2D rising.

The requirement of mitigating the environmental impact of helicopters has been addressed globally within the FRIENDCOPTER Project in the sen- se that several aspects (such as noise abatement, vibration reduction, fuel consumption) have been studied in parallel with different approaches among which there is the active blade control. In the work at hand, attention is paid on two topics aimed at mitigating helicopter environmental impact through a morphing strategy: the aerodynamic optimization of a blade section who- se camber can be affected by an actuator and the design of a SMA based static twist concept, aimed at extending the helicopter flight envelope. The latter device is based on a SMA rod which is integrated in the spanwise di- rection within the blade structure at different positions. The actuator, when heated, transmits a torque couple which induces twist onto the blade. The twist variation due to the SMA device activation has been predicted by a FE approach (MSC/Marc software implemented with the SMA Brinson model). Finally, rotor performance in hover has been estimated with the actuator in power on and off positions, highlighting benefits coming from several spanwise integrations/distributions of the SMA device.

Conservative formulations of the governing laws of elastoplastic solid media have distinct advantages when solved using high-order shock capturing methods for simulating processes involving large deformations and shock waves. In this paper one such model is considered where inelastic deformations are accounted for via conservation laws for elastic strain with relaxation source terms. Plastic deformations are governed by the relaxation time of tangential stresses. Compared with alternative Eulerian conservative models, the governing system consists of fewer equations overall. A numerical scheme For the inhomogeneous system is proposed based upon the temporal splitting. In this way the reduced system of non-linear elasticity is solved explicitly, with convective fluxes evaluated using high-order approximations of Riemann problems locally throughout the computational mesh. Numerical stiffness of the relaxation terms at high strain rates is avoided by utilizing certain properties of the governing model and performing an implicit Update. The methods are demonstrated using test cases involving large deformations and high strain rates in one-, two-, and three- dimensions. Copyright (C) 2009 John Wiley & Sons, Ltd.

The paper presents application of Implicit Large Eddy Simulation(ILES)to wall- bounded turbulent flows. A characteristics-based scheme in conjunction with total variation diminishing(TVD)Runge-Kutta time stepping and slope-limiting variants,for the com-pressible flow case, have been employed. Results are pre- sented for an incompressible lid-driven cavity flow,using an incompressible solver, and low-Mach number flows over a hill and around a delta wing, using a compressible solver. Good agreement with experimental data and numerical results using classical LES has been obtained. Future ILES developments are also discussed

The paper concerns the development of high-resolution methods for variable density flows and the implementation in multi-species flow studies in microfluidics.The high resolution discretisation is obtained by numerically reconstructing the flow variables using information for the eigenstructure of the system of equations. Three variants of high-resolution methods are presented and their accuracy is assessed against analytic and experimental results for diffusion broadening in microfluidics. Results from numerical convergence studies are also presented to demonstrate the relative efficiency of the three reconstruction variants in conjunction with first, second and third-order of accuracy in spatial discretisation.

The uid dynamics community has dealt with a number of numerical challenges since the 1950's. These include the development of numerical methods for hyperbolic conservation laws with particular interest in capturing shock wave propagation and related phenomena, solution algorithms for the solution of the incompressible Navier-Stokes equations - a numerical challenge arises here due to the absence of the pressure term from the continuity equation - methods/ techniques for the acceleration of the numerical convergence, modelling of turbulence and grid generation techniques. Within each of those areas di erent numerical approaches have been pursued by various researchers aiming to achieve higher accuracy and ef ciency of the numerical solution. Continuous interest exists in relation to the development of accurate and e cient numerical methods for the computation of instabilities, transition and turbulence. It has been observed for more than a decade that high-resolution methods can be used in (under-resolved) turbulent ow computations without the need to resort to a turbulence model, but this approach has only recently gained some theoretical support and structural explanation for the observed results [3, 15]. Because of this there is a necessary overlap between the classical modelling of turbulence and its computation through high resolution methods [5]. These methods are currently used to simulate a broad variety of complex ows, e.g., ows that are dominated by vorticity leading to turbulence, ows featuring shock waves and turbulence, and the mixing of materials [23]. Such ows are extremely dif cult to practically obtain stably and accurately in under-resolved conditions (with respect to grid resolution) using classical linear (both second and higherorder accurate) schemes. Further, new applications at micro-scale, e.g. micro uidics, microreactors and lab-on-a-chip, have raised a number of challenges for computational science methods. In this paper we provide a brief overview of highresolution methods in connection with some of the above problems. An extensive description of these methods for incompressible and low-speed Flows can be found in [5].