An experimental technique to quantify velocity field at pore scale with in microporous media, formed by packing of microglass spheres of size 200 lm inside a glass micro-model, is presented. A microparticle image velocimetry (l-PIV) system is used to study velocity fields at four different spatial regions in the microporous medium. A combined particle image velocimetry (PIV) and particle tracking velocimetry (PTV) scheme is used to quantify velocity within a typical pore size of 10-50 lm. The experiments are conducted at four different flow rates. Two different measurement planes are selected for obtaining the detailed pore scale velocity field-one close to the glass wall and the other inside the porous medium at a distance 100 lm below the glass wall. The image processing technique for dealing with noisy data and sparse vector field has been discussed in detail. Probability density functions of transverse and axial velocity components are compared with available results in literature. The pore scale velocity field obtained can provide insight to flow properties in microporous media and can be a powerful tool to validate existing numerical results for flow through porous media.
An experimental system for understanding the flow field near the meniscus during the capillarity or under capillary action is developed. Capillary flow is one of the mechanisms for driving fluid in a microfluidic device. The literature highlights that a significant amount of work has been done on the theoretical understanding of the capillary transport in rectangular microchannels. However, these models for capillary flow neglect the flow behavior at the liquid-air interface, which may have a significant influence in terms of the velocity field and the transience of the penetration depth in the micro-capillary. The objective of the present study is to understand the flow development during the advancement of the meniscus. The aim is to elucidate the dynamics of the three phase contact line and other micro-scale effects during the capillarity. A μ-PIV technique has been used to study the flow development near the meniscus and the results are further refined using a hybrid μ-PIV/PTV technique. Effects of surface tension in the fully developed flow regime during the advancement of meniscus are studied in detail. Variations in the centreline velocity of the progression of the meniscus and temporal variations in the development of flow are identified as possible areas for departure from theory.
An investigation of interstitial velocity field within a micro porous media is studied using a three component three dimensional (3C3D) μ-PIV system. The porous media is formed by packing of micro glass beads of size 400 μm inside a flow cell. The two component two dimensional (2C2D) velocity fields in micro pore region are obtained near the wall. 3C3D velocity field is obtained by scanning through 100 μm inside the porous media using the scanning μ-PIV system. Cross flow pattern and flow recirculation is observed within the micro pore region.
Abstract— The Devri‐Khera meteorite fell on 1994 October 30 in the Jhalwar district of Rajasthan, northwestern India. The texture, mineralogy and mineral and bulk compositions show that Devri‐Khera is an L6 chondrite of shock facies S4.
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