Role of Stress-controlled Flow Pathways in HDR Geothermal Reservoirs

2003 ◽  
Vol 160 (5) ◽  
pp. 1103-1124 ◽  
Author(s):  
T. Ito ◽  
K. Hayashi
Keyword(s):  
Geothermal Reservoirs ◽  
Flow Pathways ◽  
Controlled Flow

Haemorheological Effects on Thrombocyte Adhesion and Aggregation Found Under Controlled Flow Conditions

1979 ◽  
Author(s):  
P.D. Richardson
Keyword(s):  
Rate Of Change ◽  
Continuous Observation ◽  
Flow Conditions ◽  
Wide Range ◽  
Stream Migration ◽  
Local Shear ◽  
Videotape Recording ◽  
Controlled Flow ◽  
A Site

Thrombocyte adhesion and aggregation in a vessel or on a chamber wall can be measured most readily if the flow is controlled and steady, and continuous observation is used. Videotape recording is very helpful for subsequent quantification of the dynamics. The adhesion of each thrombocyte can occur for a finite time interval:this interval has been observed to have a wide range. Platelets which escape often leave open a site which attracts other platelets preferentially. The rate of change of adhesion density (platelets/mm2) is affected by the local shear rate and the shear history upstream. Aggregation is affected similarly, and also proceeds with some platelet turnover. The role of erythrocytes in facilitating cross-stream migration of thrombocytes (which can enhance the growth rate of large thrombi) appears due in part to convective flow fields induced by the motion of erythrocytes in a shear flow, which can be demonstrated theoretically and experimentally. Observations of the phenomenlogy of adhesion and aggregation under controlled flow conditions and comparison with fLu id-dynamically based theory allows representation in terras of a small number of parameters with prospects of prediction of behaviour over a wide range of haemodynamic conditions; biochemical changes lead to changes in values of the parameters, so that activating agents and inhibiting agents modify values in different directions.

The role of microporosity on the permeability of volcanic-hosted geothermal reservoirs: A case study from Los Humeros, Mexico

Geothermics ◽  
2021 ◽  
Vol 90 ◽  
pp. 102020
Author(s):  
Héctor Eduardo Cid ◽  
Gerardo Carrasco-Núñez ◽  
Vlad Constantin Manea ◽  
Sandra Vega ◽  
Victor Castaño
Keyword(s):  
Geothermal Reservoirs

Role of Actuation Frequency in Controlled Flow Reattachment over a Stalled Airfoil

AIAA Journal ◽  
2002 ◽  
Vol 40 (2) ◽  
pp. 209-216 ◽  
Author(s):  
Michael Amitay ◽  
Ari Glezer
Keyword(s):  
Actuation Frequency ◽  
Controlled Flow ◽  
Flow Reattachment

Analysis and Modelling of a Fluidic Actuator

2008 ◽  
Author(s):  
Caroline Braud ◽  
Arthur Dyment ◽  
Jim Kostas ◽  
Jean Marc Foucaut ◽  
Michel Stanislas
Keyword(s):  
Vortex Generator ◽  
Transient Behavior ◽  
Physical Parameters ◽  
Pulsed Jet ◽  
Transient Period ◽  
Fluidic Actuators ◽  
Precise Quantification ◽  
Controlled Flow ◽  
Layer Control

This paper deals with the fluidic actuators in the pulsed mode used in turbulent boundary layer control, in particular as vortex generator (VG) in order to delay separation. Recently the study by Kostas et al (2007) has shown the importance of the transient phase of the VG actuators. In particular, an enhancement of the vortex-generation mechanism has been observed during the transient period, that is responsible for an increase of turbulence stress levels up to 200% relatively to the non actuated case. A large dependency of the exit velocity on the physical characteristic of the feed tube has been detected. This dependency suggests that a precise quantification of the pulsed jet dynamic during the transient period is necessary. In this work the transient behavior of the fluidic actuators used by Kostas et al (2007) is analyzed and experimented. A model is developed to explain the dynamics of the flow inside the actuator. On the whole, experiments show that the role of all physical parameters is consistent with the foreseen properties. The results obtained help to separate the input dynamic of the controller from the controlled flow. Another perspective of this work is to provide a guide for the design of fluidic actuators.

scholarly journals Tad pili play a dynamic role in Caulobacter crescentus surface colonization

2019 ◽  
Author(s):  
Matteo Sangermani ◽  
Isabelle Hug ◽  
Nora Sauter ◽  
Thomas Pfohl ◽  
Urs Jenal
Keyword(s):  
Caulobacter Crescentus ◽  
Optical Trap ◽  
Natural Environments ◽  
Surface Attachment ◽  
Surface Colonization ◽  
Bacterial Surface ◽  
Controlled Flow ◽  
Mechanical Sensing

ABSTRACTBacterial surface attachment is mediated by rotary flagella and filamentous appendages called pili. Here, we describe the role of Tad pili during surface colonization of Caulobacter crescentus. Using an optical trap and microfluidic controlled flow conditions as a mimic of natural environments, we demonstrate that Tad pili undergo repeated cycles of extension and retraction. Within seconds after establishing surface contact, pili reorient cells into an upright position promoting walking-like movements against the medium flow. Pili-mediated positioning of the flagellated pole close to the surface facilitates motor-mediated mechanical sensing and promotes anchoring of the holdfast, an adhesive substance that affords long-term attachment. We present evidence that the second messenger c-di-GMP regulates pili dynamics during surface encounter in distinct ways, promoting increased activity at intermediate levels and retraction of pili at peak concentrations. We propose a model, in which flagellum and Tad pili functionally interact and together impose a ratchet-like mechanism that progressively drives C. crescentus cells towards permanent surface attachment.

scholarly journals The role of heterogeneous lithology in a glaciofluvial deposit on unsaturated preferential flow – a numerical study

2017 ◽  
Vol 65 (3) ◽  
pp. 209-221 ◽  
Author(s):  
Erij Ben Slimene ◽  
Laurent Lassabatere ◽  
Jiří Šimůnek ◽  
Thierry Winiarski ◽  
Remy Gourdon
Keyword(s):  
Urban Areas ◽  
Hydraulic Properties ◽  
Preferential Flow ◽  
Numerical Study ◽  
Full Characterization ◽  
Capillary Barriers ◽  
Flow Pathways ◽  
Preferential Flow Pathways

AbstractAn understanding of preferential flow in the vadose zone is crucial for the prediction of the fate of pollutants. Infiltration basins, developed to mitigate the adverse effects of impervious surfaces in urban areas, are established above strongly heterogeneous and highly permeable deposits and thus are prone to preferential flow and enhanced pollutant transport. This study numerically investigates the establishment of preferential flow in an infiltration basin in the Lyon suburbs (France) established over a highly heterogeneous glaciofluvial deposit covering much of the Lyon region. An investigation of the soil transect (13.5 m long and 2.5 m deep) provided full characterization of lithology and hydraulic properties of present lithofacies. Numerical modeling with the HYDRUS-2D model of water flow in the transect was used to identify the effects of individual lithofacies that constitute the deposit. Multiple scenarios that considered different levels of heterogeneity were evaluated. Preferential flow was studied for several values of infiltration rates applied after a long dry period. The numerical study shows that the high contrast in hydraulic properties of different lithofacies triggers the establishment of preferential flow (capillary barriers and funneled flow). Preferential flow develops mainly for low water fluxes imposed at the surface. The role of individual lithofacies in triggering preferential flow depends on their shapes (layering versus inclusions) and their sizes. While lenses and inclusions produce preferential flow pathways, the presence of the surface layer has no effect on the development of preferential flow and it only affects the effective hydraulic conductivity of the heterogeneous transect.

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