naa a22 4500 510749763 CHVBK 20180411083100.0 cr unu---uuuuu 180411e20130901xx s 000 0 eng 10.1007/s11270-013-1666-2 doi (NATIONALLICENCE)springer-10.1007/s11270-013-1666-2 Minor Losses During Air Flow into Granular Porous Media [Elektronische Daten] [Tjalfe Poulsen, Greta Minelgaite, Thomas Bentzen, Rune Andreasen] Pressure gradients during uniform fluid flow in porous media are traditionally assumed to be linear. Thus, pressure loss across a sample of porous medium is assumed directly proportional to the thickness of the sample. In this study, measurements of pressure gradients inside coarse granular (2-18mm particle size) porous media during steady gas flow were carried out. The results showed that pressure variation with distance in the porous media was nonlinear near the inlet (where pressure gradients were higher) but became linear at greater distances (with a lower gradient). This indicates that the pressure loss in porous media consists of two components: (1) a linear pressure gradient and (2) an initial pressure loss near the inlet. This initial pressure loss is also known from hydraulics in tubes as a minor loss and is associated with abrupt changes in the flow field such as narrowings and bends. The results further indicated that the minor loss depends on the particle size and particle size distribution in a manner similar to that of the linear pressure gradient. There is, thus, a close relation between these two components. In porous media, the minor loss is not instantaneous at the inlet point but happens over some distance starting upstream from the inlet and ending some distance downstream. Springer Science+Business Media Dordrecht, 2013 Granular porous media nationallicence Fluid flow nationallicence Fluid pressure loss nationallicence Minor losses nationallicence Pressure gradient nationallicence Particle size distribution nationallicence Poulsen Tjalfe Department of Civil Engineering, Xi'an Jiaotong-Liverpool University, 111 Ren Ai Rd, 215123, Suzhou, China aut Minelgaite Greta Section for Water and Environment, Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, 9000, Aalborg, Denmark aut Bentzen Thomas Section for Water and Environment, Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, 9000, Aalborg, Denmark aut Andreasen Rune Department of Agroecology, Aarhus University, Blichers Allé 20, 8830, Tjele, Denmark aut Water, Air, & Soil Pollution Springer Netherlands 224/9(2013-09-01), 1-11 0049-6979 224:9<1 2013 224 11270 https://doi.org/10.1007/s11270-013-1666-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11270-013-1666-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Poulsen Tjalfe Department of Civil Engineering, Xi'an Jiaotong-Liverpool University, 111 Ren Ai Rd, 215123, Suzhou, China aut NATIONALLICENCE 700 1- Minelgaite Greta Section for Water and Environment, Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, 9000, Aalborg, Denmark aut NATIONALLICENCE 700 1- Bentzen Thomas Section for Water and Environment, Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, 9000, Aalborg, Denmark aut NATIONALLICENCE 700 1- Andreasen Rune Department of Agroecology, Aarhus University, Blichers Allé 20, 8830, Tjele, Denmark aut NATIONALLICENCE 773 0- Water, Air, & Soil Pollution Springer Netherlands 224/9(2013-09-01), 1-11 0049-6979 224:9<1 2013 224 11270 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer