Modelling of two-component turbulent mass and heat transfer in air-fed pressurised suits

This article has been accepted for publication in the Flow, Turbulence and Combustion journal.In this paper the modelling of an important industrial problem is addressed, which involves the two-component turbulent flow with heat transfer that takes place inside protective clothing. The geometry of the flow boundaries is reconstructed in a CAD system from photogrammetry scan data. The overall model is sufficiently realistic to allow, after validation, design improvements to be tested. Those presented here allow the reduction of hot spots over the worker’s body surface and increase thermal comfort.This project is funded by the Engineering and Physical Sciences Research Council and the UK Atomic Energy Authority

Colour in visualisation for computational fluid dynamics

Colour is used in computational fluid dynamic (CFD) simulations in two key ways. First it is used to visualise the geometry and allow the engineers to be confident that the model constructed is a good representation of the engineering situation. Once an analysis has been completed, colour is used in post-processing the data from the simulations to illustrate the complex fluid mechanic phenomena under investigation. This paper describes these two uses of colour and provides some examples to illustrate the key visualisation approaches used in CFD

A thermo-fluid model for protective suiting used in fusion reactor shutdown operations

In this paper we report a method of modelling the overall thermo-fluid processes which occur in protective suiting as used in the Joint European Torus (JET) fusion reactor at Culham, UK. It had three main objectives: to be as basic and comprehensive as possible, to have an ability to model real situations and suiting, and hence to provide a tool for improvements in design. Basic thermo-fluids equations for multi-component and multi-phase flow have been developed within commercial Computational Fluid Dynamics (CFD) software to address the heat and mass (moisture) transfer processes. This is combined with a human metabolic heat load model to simulate working operations. Finally, a particular feature is the definition of the 3-D human body/suit microclimate, via the use of an unsuited and suited mannequin. This involved a geometrical reconstruction method developed from the point cloud data given by photogrammetry. Examples of predicted temperature distributions are compared with experimental data to show the potential of the model we have used

Heat and mass transfer in air-fed pressurised suits

Air-fed pressurised suits are used to protect workers against contamination and hazardous environments. The specic application here is the necessity for regular clean-up maintenance within the torus chamber of fusion reactors. The current design of suiting has been developed empirically. It is, therefore, very desirable to formulate a thermofluids model, which will be able to define optimum designs and operating parameters. Two factors indicate that the modelling should be as comprehensive as possible. Firstly, the overall thermofluids problem is three-dimensional and includes mass as well as heat transfer. The fluid field is complex, bounded on one side by the human body and on the other by what may be distensible, porous and multi-layer clothing. In this paper, we report firstly the modelling necessary for the additional mass and heat transport processes. This involves the use of Fick's and Fourier's laws and conjugate heat transfer. The results of an initial validation study are presented. Temperatures at the outlet of the suits were obtained experimentally and compared with those predicted by the overall CFD model. Realistic three-dimensional geometries were used for the suit and human body. Calculations were for turbulent flow with single- and two-component (species) models

Determination of Chlorinated organic compounds in aqueous matrices

Thirteen pure volatile, semi-volatile and non-volatile chlorinated organic compounds of molecular weights ranging from trichloroethylene (MW = 131.39 g mole -¹) to hexachlorobenzene (MW = 284.78 g mole-¹) were determined in aqueous matrices by GC-ECD. After 10% salt addition, different extraction tests were performed using fibres whose adsorbing phase was based on microsphere carbon particles characterized by a constant size. Five experimental parameters were optimized: extraction temperature and time, position of the fibre in the GC injector port, desorption temperature and time. The optimized analytical protocol was employed to determine the efficiency of a real activated carbon adsorption plant to remove organic chlorinated pollutants from an industrial wastewater at ng l-¹ levels

Sorafenib dose escalation is not uniformly associated with blood pressure elevations in normotensive patients with advanced malignancies.

Hypertension after treatment with vascular endothelial growth factor (VEGF) receptor inhibitors is associated with superior treatment outcomes for advanced cancer patients. To determine whether increased sorafenib doses cause incremental increases in blood pressure (BP), we measured 12-h ambulatory BP in 41 normotensive advanced solid tumor patients in a randomized dose-escalation study. After 7 days' treatment (400 mg b.i.d.), mean diastolic BP (DBP) increased in both study groups. After dose escalation, group A (400 mg t.i.d.) had marginally significant further increase in 12-h mean DBP (P = 0.053), but group B (600 mg b.i.d.) did not achieve statistically significant increases (P = 0.25). Within groups, individuals varied in BP response to sorafenib dose escalation, but these differences did not correlate with changes in steady-state plasma sorafenib concentrations. These findings in normotensive patients suggest BP is a complex pharmacodynamic biomarker of VEGF inhibition. Patients have intrinsic differences in sensitivity to sorafenib's BP-elevating effects

Revisiting Frank–Starling: regulatory light chain phosphorylation alters the rate of force redevelopment (k<inf>tr</inf>) in a length-dependent fashion

© 2016 Wellcome Trust. Key points: Regulatory light chain (RLC) phosphorylation has been shown to alter the ability of muscle to produce force and power during shortening and to alter the rate of force redevelopment (ktr) at submaximal [Ca2+]. Increasing RLC phosphorylation ∼50% from the in vivo level in maximally [Ca2+]-activated cardiac trabecula accelerates ktr. Decreasing RLC phosphorylation to ∼70% of the in vivo control level slows ktr and reduces force generation. ktr is dependent on sarcomere length in the physiological range 1.85–1.94 μm and RLC phosphorylation modulates this response. We demonstrate that Frank–Starling is evident at maximal [Ca2+] activation and therefore does not necessarily require length-dependent change in [Ca2+]-sensitivity of thin filament activation. The stretch response is modulated by changes in RLC phosphorylation, pinpointing RLC phosphorylation as a modulator of the Frank–Starling law in the heart. These data provide an explanation for slowed systolic function in the intact heart in response to RLC phosphorylation reduction. Abstract: Force and power in cardiac muscle have a known dependence on phosphorylation of the myosin-associated regulatory light chain (RLC). We explore the effect of RLC phosphorylation on the ability of cardiac preparations to redevelop force (ktr) in maximally activating [Ca2+]. Activation was achieved by rapidly increasing the temperature (temperature-jump of 0.5–20ºC) of permeabilized trabeculae over a physiological range of sarcomere lengths (1.85–1.94 μm). The trabeculae were subjected to shortening ramps over a range of velocities and the extent of RLC phosphorylation was varied. The latter was achieved using an RLC-exchange technique, which avoids changes in the phosphorylation level of other proteins. The results show that increasing RLC phosphorylation by 50% accelerates ktr by ∼50%, irrespective of the sarcomere length, whereas decreasing phosphorylation by 30% slows ktr by ∼50%, relative to the ktr obtained for in vivo phosphorylation. Clearly, phosphorylation affects the magnitude of ktr following step shortening or ramp shortening. Using a two-state model, we explore the effect of RLC phosphorylation on the kinetics of force development, which proposes that phosphorylation affects the kinetics of both attachment and detachment of cross-bridges. In summary, RLC phosphorylation affects the rate and extent of force redevelopment. These findings were obtained in maximally activated muscle at saturating [Ca2+] and are not explained by changes in the Ca2+-sensitivity of acto-myosin interactions. The length-dependence of the rate of force redevelopment, together with the modulation by the state of RLC phosphorylation, suggests that these effects play a role in the Frank–Starling law of the heart.Wellcome Trust Grant 091460/Z/10/Z

Velocity profile development and friction in compressible micro flows

From Poiseuille theory, it is known that incompressible laminar fully-developed flow of a Newtonian fluid in a constant cross-section channel is characterised by steady parabolic velocity profiles after a fully-developed flow condition is attained. In turbulent fully-developed flow the velocity profiles are non-parabolic and become more flat for higher Reynolds numbers. When the incompressible hypothesis does not hold, as in the case of high velocity ideal gas flow, the velocity profile becomes flatter, as if more turbulent, due to the superposition of compressibility and turbulence effects, if applicable. This is typical in microchannel flows, where pressure gradients are high and the gas is rapidly accelerating, eventually up to the sound velocity. As the flow accelerates the effects of compressibility grow stronger and the velocity profile keeps changing shape. The radial velocity component does not zero as in fully-developed flow but reverses after the entrance effects have damped out and grows with the Mach number. A net mass transfer toward the walls is thus generated making the velocity profile more flat. This affects the friction factor which is no longer constant, being proportional to the normal-to-wall velocity gradient, and needs to be evaluated. In the present work, the compressible friction factor is numerically investigated and correlations are proposed based on the velocity profile shape evolution as a function of the Mach number. This, together with other considerations on the velocity profile shape change, is shown to enhance the predictive capability of the Fanno theory for compressible flows