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GAS DISPERSION IN HIGHLY VISCOUS NON-NEWTONIAN FLUIDS USING EXTRUDER-FEEDER.Khan, Mohammad Bilal. January 1984 (has links)
No description available.
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Modelling of installation effects on transit time ultrasonic flow meters in circular pipesMoore, Pamela I. January 2001 (has links)
No description available.
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Organometallic based transition metal catalystsKerton, Francesca Maria January 1998 (has links)
No description available.
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Vorticity alignment phenomena in the three dimensional Euler and Navier-Stokes equationsHeritage, Matthew Christopher January 1998 (has links)
No description available.
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Particulate moulding : experimental analysis and computational modelling using boundary element methodOgdhoh, Shem Odhiambo January 1998 (has links)
No description available.
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Vortex cloud modelling for axisymmetric flowsMing, Li January 1995 (has links)
No description available.
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Nonazeotropic mixtures as working fluids for heat pumpsPatwardhan, V. R. January 1987 (has links)
No description available.
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Conditional and unconditional nonlinear stability in fluid dynamicsBudu, Paula January 2002 (has links)
In this thesis we examine some of the interesting aspects of stability for some convection problems. Specifically, the first part of the thesis deals with the Bénard problem for various Non-Newtonian fluids, whereas the second part develops a stability analysis for convection in a porous medium. The work on stability for viscoelastic fluids includes nonlinear stability analyses for the second grade fluid, the generalised second grade fluid, the fluid of dipolar type and the fluid of third grade. It is worth remarking that throughout the work the viscosity is supposed to be any given function of temperature, with the first derivative bounded above by a positive constant. The connection between the two parts of the thesis is made through the method used to approach the nonlinear stability analysis, namely the energy method. It is shown in the introductory chapter how this method works and what are its advantages over the linear analysis. Nonlinear stability results established in both Part I and Part II are the best one can get for the considered physical situations. Different choices of energy have been considered in order to achieve conditional or unconditional nonlinear stability results.
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Lactate accumulation during exercise - the influence of body fluid shifts.Castleman, Barbara Ann 25 June 1999 (has links)
Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Medicine, 1998. / During graded exercise, an intensity is reached where a subjects
ability to remove lactate lags behind the rate of lactace
production. The influence of body fluid shifts, during exercise
of increasing intensity, on the pattern of the blood lactate
response was studied.
The maximal oxygen uptake (V02 max) was measured using a
treadmill, on eleven subjects. Subsequently, lactate
accumulation in venous blood was measured, in triplicate, up to
an oxygen consumption greater than 90% V02max. During all
exercise, oxygen consumption was measured using an online system.
In addition, the blood samples at each workload were used to
determine haematocrit (Hct) and haemoglobin (Hb) levels.
The Hct and Hb values were used to calculate lactate accumulation
(corrected for body fluid shifts) as opposed to the absolute or
total lactate levels. The correction for body fluid shifts was
done using two techniques. The one using haematocrit only and the
other using both haematocrit and haemoglobin. The total and
accumulated lactate levels were related to %V02max using two
different models. Firstly, a lactate threshold (LT) was
determined using the classic lactate turning point (LTP) concept,
(ie. two straight lines fitted to the data points) . These Tines
iii
were computer generated. The intercept of the two lines (LT) was
compared for total lactate against accumulated lactate
(calculated using Hct alone and secondly Hct in combination with
Hb. In the latter cases, both the LT intercepts were shifted
slightly to the right (ie. to a higher % of V02max) . The average
difference in LT when adjusting with Hb and Hct was 0,519 of
%V02max (0,72% change) and when adjusting with Hct only was 1,17
of %V02 max (1,65% change).
Secondly, an exponential curve was fitted by regression to the
data (r=0.989+/-0.018). A substantial shift in the curve, both
down and to the right, was obtained when adjusting total lactate
to accumulated lactate. The %V02 max at a lactate concentration
of 4 mmol/I was used to define the position of the curve. The
difference when using Hct alone to calculate accumulated lactate
corrected for fluid shift was - 9,20% of V02max (p<0.05), and
when using Hb and Hct in combination, -8,71% of V02max (p<0,05) .
It is concluded that expressing the lactate curve as an
accumulated curve (corrected for body fluid shifts), rather than
in absolute terms, significantly alters the construction of the
curve during the exercise protocol used in this study. This is
especially relevant when using the exponential model,
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Finite size particle transport in turbulent channel flow / Transport de particules de taille finie par la turbulence de paroiYu, Wenchao 08 December 2015 (has links)
Le transport de particules solides par les écoulements turbulents près des parois est l'objet de nombreuses applications environnementales telles que les problèmes d'érosion, de dépôt ou de particules de sable en saltation. Malgré les progrès dans les techniques expérimentales et les simulations, des interrogations persistent dans la compréhension des mécanismes de transport des particules près de la paroi. Nombreuses études ont été consacrées à ce problème. Par simulationnumerique directe (DNS) couplée avec le suivi lagrangien de particules ponctuelles, Zamansky et al. (2011) ont trouvé que contrairement à ce qui est observé en turbulence homogène isotrope, près de la paroi les particules solides se concentrent de manière préférentielle dans les régions de forte RMS d'acceleration longitudinale. L'objectif de ce travail est de vérifier si cette observation est toujours vraie lorsque la taille des particules est prise en compte dans les simulations. Pour cela, un code pseudo-spectral de DNS est couplé avec une méthode de frontières immergées (Uhlmann, 2005). Le couplage est valide dans différents cas en 2D ou 3D d'obstacles fixes ou en déplacement. Un bon accord est atteint avec les résultats d'autres études expérimentales ou numériques. Ensuite, des particules de taille finie avec différents nombres de Stokes et densités sont suivies à chaque instant dans un écoulement de canal turbulent. Les statistiques de vitesse et d'accélération sont analysées. Un intérêt particulier est porté sur les PDF d'accélération des particules, du fluide et du fluide au voisinage des particules. Dans la mesure du possible, les résultats sont comparés à ceux obtenus par le suivi lagrangien de particules ponctuelles / Particle transport by turbulent wall flow is a crucial issue in many environmental problems such as erosion, particle deposition and sand saltation. Despite great technological advances in measurement techniques as well as in numerical simulations, the understanding of the transport mechanism close to the wall is still incomplete. Many numerical studies have been devoted to this issue. By direct numerical simulations (DNS) of a turbulent channel flow coupled with Lagrangian tracking of pointwise particles, Zamansky et al. (2011) found that contrary to what is observed in homogeneous isotropic turbulence, close to the wall pointwise particles cluster in regions of high streamwise RMS acceleration. The aim of the present study is to explore if this is still the case when size effects are taken into account in the DNS. Therefore, a pseudo-spectral DNS code is coupled with an immersed boundary technique (Uhlmann, 2005). The coupling is validated in the case of 2D and 3D moving and fixed bodies. Good agreement is achieved with other experimental and numerical studies. Then, finite-size particles with different Stokes numbers and density ratios are tracked at each time step in a turbulent channel flow. The velocity and acceleration statistics are analyzed. Particular attention is given to acceleration PDF of the solid phase, the fluid phase and the fluid in the vicinity of particles. The results are compared to the pointwise model
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