Heat flow across the toe of accretionary prisms - The role of fluid flux

1993 ◽  
Vol 20 (8) ◽  
pp. 659-662 ◽  
Author(s):  
Chi-yuen Wang ◽  
Guoping Liang ◽  
Yaolin Shi
Keyword(s):  
Heat Flow ◽  
Fluid Flux ◽  
Accretionary Prisms

scholarly journals Effect of time and vascular pressure on permeability and cyclic nucleotides in ischemic lungs

2000 ◽  
Vol 279 (5) ◽  
pp. H2077-H2084 ◽  
Author(s):  
David B. Pearse ◽  
Patrice M. Becker
Keyword(s):  
Nitric Oxide ◽  
High Pressure ◽  
Reflection Coefficient ◽  
Cyclic Nucleotides ◽  
Fluid Flux ◽  
No Donor ◽  
Independent Mechanism ◽  
Dependent Mechanism ◽  
Intravascular Pressure

We previously found that increased intravascular pressure decreased ischemic lung injury by a nitric oxide (NO)-dependent mechanism (Becker PM, Buchanan W, and Sylvester JT. J Appl Physiol 84: 803–808, 1998). To determine the role of cyclic nucleotides in this response, we measured the reflection coefficient for albumin (ςalb), fluid flux ( J˙), cGMP, and cAMP in ferret lungs subjected to either 45 min (“short”; n = 7) or 180 min (“long”) of ventilated ischemia. Long ischemic lungs had “low” (1–2 mmHg, n = 8) or “high” (7–8 mmHg, n = 6) vascular pressure. Other long low lungs were treated with the NO donor ( Z)-1-[ N-(3-ammoniopropyl)- N-( n-propyl)amino]diazen-1-ium-1,2-diolate (PAPA-NONOate; 5 × 10−4 M, n = 6) or 8-bromo-cGMP (5 × 10−4 M, n = 6). Compared with short ischemia, long low ischemia decreased ςalb (0.23 ± 0.04 vs. 0.73 ± 0.08; P < 0.05) and increased J˙ (1.93 ± 0.26 vs. 0.58 ± 0.22 ml · min−1 · 100 g−1; P < 0.05). High pressure prevented these changes. Lung cGMP decreased by 66% in long compared with short ischemia. Lung cAMP did not change. PAPA-NONOate and 8-bromo-cGMP increased lung cGMP, but only 8-bromo-cGMP decreased permeability. These results suggest that ischemic vascular injury was, in part, mediated by a decrease in cGMP. Increased vascular pressure prevented injury by a cGMP-independent mechanism that could not be mimicked by administration of exogenous NO.

Fibronectin deficiency and intestinal transvascular fluid balance during bacteremia

1982 ◽  
Vol 242 (4) ◽  
pp. H557-H564
Author(s):  
B. C. Dillon ◽  
T. M. Saba
Keyword(s):  
Vascular Permeability ◽  
Fluid Balance ◽  
Protein Concentration ◽  
Lymph Flow ◽  
Fluid Flux ◽  
Fluid Filtration ◽  
Coated Particles ◽  
P Protein ◽  
Small Intestinal

Reticuloendothelial (RE) clearance dysfunction, which can be induced by opsonic fibronectin deficiency, has been correlated with organ failure during sepsis. We investigate the role of opsonic fibronectin deficiency and RE blockade in modulating alterations in intestinal transvascular fluid balance induced by Pseudomonas bacteremia using an isolated, innervated, and autoperfused canine small intestinal segment. Intravenous infusion of gelatin-coated particles was used to induce fibronectin deficiency and RE blockade. Lymph flow and lymph/plasma (L/P) protein concentration ratios were stable following intravenous challenge with bacteria or gelatin-coated particles. In contrast, lymph flow increased and L/P ratio decreased significantly when bacteremia coexisted with particle-induced opsonic fibronectin deficiency and RE blockade. This elevation in lymph flow and decline in L/P ratio was associated with normal vascular permeability to albumin, IgG, and IgM. The increase in intestinal fluid flux during bacteremia with RE blockade appears to be due to an increase in microvascular hydrostatic pressure and not to an increase in vascular permeability. These findings emphasize a potentially important role for fibronectin and associated RE system function as determinants of fluid filtration during sepsis.

Heat Flow and Fluid Flux in Cascadia's Seismogenic Zone

Eos ◽  
2013 ◽  
Vol 94 (48) ◽  
pp. 457-458 ◽  
Author(s):  
H. Paul Johnson ◽  
Evan A. Solomon ◽  
Robert N. Harris ◽  
Marie S. Salmi ◽  
Richard D. Berg
Keyword(s):  
Heat Flow ◽  
Seismogenic Zone ◽  
Fluid Flux

Natural convection in a corrugated slot

2017 ◽  
Vol 815 ◽  
pp. 537-569 ◽  
Author(s):  
Arman Abtahi ◽  
J. M. Floryan
Keyword(s):  
Natural Convection ◽  
Heat Flow ◽  
Convective Heat ◽  
Phase Difference ◽  
Conductive Heat ◽  
Heat Transfer Augmentation ◽  
Conductive Heat Flow ◽  
Secondary Motion ◽  
Prandtl Numbers

Analysis of natural convection in a horizontal slot formed by two corrugated isothermal plates has been carried out. The analysis is limited to subcritical Rayleigh numbers$Ra$where no secondary motion takes place in the absence of corrugations. The corrugations have a sinusoidal form characterized by the wavenumber, the upper and lower amplitudes and the phase difference. The most intense convection occurs for corrugation wavelengths comparable to the slot height; it increases proportionally to$Ra$and proportionally to the corrugation height. Placement of corrugations on both plates may either significantly increase or decrease the convection depending on the phase difference between the upper and lower corrugations, with the strongest convection found for corrugations being in phase, i.e. a ‘wavy’ slot, and the weakest for corrugations being out of phase, i.e. a ‘converging–diverging’ slot. It is shown that the shear forces would always contribute to the corrugation build-up if erosion was allowed, while the role of pressure forces depends on the location of the corrugations as well as on the corrugation height and wavenumber, and the Rayleigh number. Placing corrugations on both plates results in the formation of a moment which attempts to change the relative position of the plates. There are two limiting positions, i.e. the ‘wavy’ slot and the ‘converging–diverging’ slot, with the latter being unstable. The system would end up in the ‘wavy’ slot configuration if relative movement of the two plates was allowed. The presence of corrugations affects the conductive heat flow and creates a convective heat flow. The conductive heat flow increases with the corrugation height as well as with the corrugation wavenumber; it is largest for short-wavelength corrugations. The convective heat flow is relevant only for wavenumbers of$O(1)$, it increases proportionally to$Ra^{3}$and proportionally to the second power of the corrugation height. Convection is qualitatively similar for all Prandtl numbers$Pr$, with its intensity increasing for smaller$Pr$and with the heat transfer augmentation increasing for larger$Pr$.

scholarly journals From arteries to boreholes: transient response of a poroelastic cylinder to fluid injection

2018 ◽  
Vol 474 (2216) ◽  
pp. 20180284 ◽  
Author(s):  
L. C. Auton ◽  
C. W. MacMinn
Keyword(s):  
Transient Response ◽  
Large Deformations ◽  
Fluid Pressure ◽  
Soft Materials ◽  
Fluid Injection ◽  
Solid Skeleton ◽  
Fluid Flux ◽  
Vascular Walls ◽  
Initial Geometry

The radially outward flow of fluid through a porous medium occurs in many practical problems, from transport across vascular walls to the pressurization of boreholes in the subsurface. When the driving pressure is non-negligible relative to the stiffness of the solid structure, the poromechanical coupling between the fluid and the solid can control both the steady state and the transient mechanics of the system. Very large pressures or very soft materials lead to large deformations of the solid skeleton, which introduce kinematic and constitutive nonlinearity that can have a non-trivial impact on these mechanics. Here, we study the transient response of a poroelastic cylinder to sudden fluid injection. We consider the impacts of kinematic and constitutive nonlinearity, both separately and in combination, and we highlight the central role of driving method in the evolution of the response. We show that the various facets of nonlinearity may either accelerate or decelerate the transient response relative to linear poroelasticity, depending on the boundary conditions and the initial geometry, and that an imposed fluid pressure leads to a much faster response than an imposed fluid flux.

Study of the Thermal-Structural Behavior of a Piston Diesel With Gallery Through Finite Element Method

2012 ◽  
Author(s):  
José Manuel Avila Aguilar ◽  
Raul Lesso Arroyo ◽  
Jorge Martínez Cruz
Keyword(s):  
Finite Element ◽  
Heat Flow ◽  
Interaction Analysis ◽  
The Body ◽  
Field Analysis ◽  
Element Analysis ◽  
Finite Element Software ◽  
Piston Head ◽  
The Finite Element Analysis

The finite element analysis is a useful tool to investigate the behavior of a body subjected to different loads. The objective of this work was the analysis of an aluminum diesel piston provided with a cooling gallery, Cu-Zn bushings, and a Ni-resist insert. This piston is used in 1.9 L turbodiesel engines. The investigation was undertaken in order to observe the mechanical behavior of the piston at the operating temperatures and pressures and thus to study the performance of the different parts of the piston. The analysis was performed using a finite element software, taking into account a coupled field analysis and involving a fluid passing through the cooling gallery, temperature and pressure at the piston head which resulted in heat flow and thermo-mechanical stresses in the piston. According to the obtained results, it is worth noting the important role of Cu-Zn bushings in the piston as they support the highest stress of about 359 MPa and protect the piston against failure, and these bushings are able to support more stress that the body of the piston (aluminum yield stress limit 290 MPa). Also it is observed that the cooling gallery acts as a thermal barrier by preventing the heat flow from the head piston (approximately 213 ° C) toward the piston body (approximately 80 ° C). Another important aspect is the structural thermal interaction analysis and it can be observed the influence of high temperatures in the piston, increasing stress up to 100%. Finally it was concluded that the piston is able to withstand the operating pressures and temperatures.

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