flow visualization techniques using tracer markers such as die, smoke, hydrogen bubbles, etc., have been widely used in experimental investigations of large scale structures of a variety of flow fields. they have played an important role in understanding the physics of the coherent structures formation and evolution in the transitional as well as the turbulent regions of the flow fields. howeve...

PURPOSE To provide transcranial color-coded duplex flow-velocity data for the basal cerebral arteries in patients with unilateral flow-restrictive extracranial carotid artery disease, and to compare these data with the flow velocities obtained in healthy control subjects. METHODS Transcranial color-coded duplex sonography was performed in 78 patients with different patterns of cross flow thro...

An experimental study of Taylor’s hypothesis in a quasi-two-dimensional turbulent soap film is presented. A two probe laser Doppler velocimeter enables a non-intrusive simultaneous measurement of the velocity at spatially separated points. The breakdown of Taylor’s hypothesis is quantified using the cross correlation between two points displaced in both space and time; correlation is better tha...

An experimental study of Taylor’s hypothesis in a quasi-two-dimensional turbulent soap film is presented. A two probe laser Doppler velocimeter enables a non-intrusive simultaneous measurement of the velocity at spatially separated points. The breakdown of Taylor’s hypothesis is quantified using the cross correlation between two points displaced in both space and time; correlation is better tha...

Defocusing digital particle image velocimetry (DDPIV) is the natural extension of planar PIV techniques to the third spatial dimension. In this paper we give details of the defocusing optical concept by which scalar and vector information can be retrieved within large volumes. The optical model and computational procedures are presented with the specific purpose of mapping the number density, t...

Usually, in concentration polarization models, the mass transfer coefficient is an unknown parameter. Also, its variation with changing experimental circumstances is in question. In the literature, many relationships can be found to describe the mass transfer coefficient under various conditions, as well as various corrections for deviating behaviour during ultrafiltration. To obtain reliable m...

Cylindrical structures in a group are frequently seen on land and in the ocean. Mutual flow interaction between the structures makes the wake very excited or tranquil depending on the spacing between the structures. The excited wake-enhancing forces in some cases cause a catastrophic failure of the structures. This paper presents results of an experimental investigation of Strouhal number (St),...

An experimental investigation of the cake filtration behaviour of 125-180 pm polyethylene particles, suspended in a neutrally buoyant Newtonian fluid, has been carried out. Static cake filtration measurements of both filtrate volume out-flow and cake thickness kinetics show the familiar t”” time dependence. In addition, the hydraulic resistance of the cake was found to be pressure independent, ...

It has been subjected to the Agency's peer and administrative reviews and has been approved for publication as an EPA document. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use. iii Foreword The U. S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's land, air, and water resources. Under a mandate ...