scholarly journals Visualization and Measuament of Velocity Field in Pulsatile Flow through a Curved Tube of Square Cross Section Using Laser-Induced Fluorescence Method.

1991 ◽  
Vol 11 (Supplement1) ◽  
pp. 149-152
Author(s):  
Tomohiro TAKEGAMI ◽  
Kenkichi OHBA ◽  
Yoshiyuki FUTAGAMI
Keyword(s):  
Velocity Field ◽  
Cross Section ◽  
Pulsatile Flow ◽  
Laser Induced Fluorescence ◽  
Fluorescence Method ◽  
Curved Tube ◽  
Flow Through

scholarly journals Elucidating changes in the degree of tracer dispersion in a subglacial channel

2003 ◽  
Vol 37 ◽  
pp. 275-280 ◽  
Author(s):  
Thomas Schuler ◽  
Urs H. Fischer
Keyword(s):  
Velocity Field ◽  
Cross Section ◽  
Field Experiments ◽  
Velocity Dispersion ◽  
Drainage System ◽  
Tracer Transport ◽  
Flow Solver ◽  
Dispersion Relationship ◽  
Tracer Dispersion ◽  
Flow Through

AbstractTracer injections into a subglacial channel at Unteraargletscher, Switzerland, were repeated at intervals of about 2 hours over two diurnal discharge cycles in August and September 2000. Records of dye concentration reveal a pronounced hysteresis in the velocity–dispersion relationship, thereby indicating alterations in the drainage system. Theoretical considerations for Röthlisberger channels suggest an evolution of the conduit cross-section in response to a diurnally varying discharge. We studied the relation between conduit cross-section and tracer dispersion with numerical tracer experiments. The velocity field for steady flow through a given conduit geometry is calculated using a commercial flow solver. Tracer transport is represented by a scalar volume which is advected by the velocity field. Experiments were conducted for several scenarios by varying flow velocity, conduit geometry and conduit roughness. Results show only a weak dependence of dispersion on conduit size. In contrast, changes in roughness of the conduit walls reveal a strong effect on tracer dispersion. Therefore, to explain the observed hysteresis in the velocity–dispersion relationship, we suggest that the evolution of a subglacial flow path might involve changes in roughness.

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