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Sand for Filtration in Water Quality Control: Criteria and Mode of Action
Published in Willy J. Masschelein, Unit Processes in Drinking Water Treatment, 2020
The following design parameters are involved in establishing the washing devices of filters. The main loss of pressure is the loss of head in the system of drains or in porous plates of the filter bottoms.The loss of head of the filter bed in expansion: This is equal to the apparent weight of the filter mass in water.All the hydraulic head losses in the repartition pipes of the valves, the sudden outlets, and so on, that are specific for each installation and must be calculated on the usual basis.In the alternative of filters provided with a layer of support gravel, the head losses in the gravel, which can be evaluated according to the equations of the porous medium, must also be added. In general, they are less than 20 to 30 cm.
Flow of Fluids in Food Processing
Published in Susanta Kumar Das, Madhusweta Das, Fundamentals and Operations in Food Process Engineering, 2019
Susanta Kumar Das, Madhusweta Das
At minimum fluidization velocity u¯oM (porosity εM), drag force (i.e. Δpαb) is counterbalanced by the apparent weight of the bed. With true density of solid ρp, Δp is computed from the following equation: Δp=αbh(1−εM)ρpg−αbh(1−εM)ρfgαb=(1−εM)(ρp−ρf)hg
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Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[fluid dynamics, general] [ref. mechanics] (syn.: Float, Archimedes’ principle) {use: biomedical, statics} An object submerged in a fluid medium (liquid or gas) will experience an apparent weight that is its own weight reduced by the weight of the volume of the displaced fluid. This phenomenon was first described by the Greek physicist Archimedes (287–212 BC) in approximately 214 BC, while taking a bath. Surface tension will affect the total outcome of the apparent weight. The Archimedes principle can be used to derive the density (ρ) of an unknown object. Additionally, the relative composition of components can be established, such as the amount of body fat or the gold content. The upward (buoyancy-) force is defined as Fb=ρlVlg, where Vl is the volume and ρl is the density of the displaced fluid. Technically, the forces are vectors, and hence, a negative sign means against the direction of gravitational acceleration, also known as Archimedes’ principle (see Figure B.72).
Magnitude of vertical ground reaction force during water-based exercises in women with obesity
Published in Sports Biomechanics, 2021
Cristine Lima Alberton, Bruna Amaral Fonseca, Gabriela Neves Nunes, Marco Bergamin, Stephanie Santana Pinto
The effectiveness of water-based exercises in individuals with obesity has already been demonstrated in literature. Studies verified that individuals with obesity may have similar cardiorespiratory capacity and body composition improvements when performing water-based in comparison to land-based exercise programmes (Gappmaier et al., 2006; Greene et al., 2009; Lopera et al., 2016). On the other hand, to the best of authors’ knowledge, no study assessed the apparent weight reduction and the magnitude of vertical ground reaction force (Fz) during water-based exercises in this population. In the last two decades, studies have demonstrated an important reduction on Fz during different types of exercises performed by young eutrophic individuals in the aquatic environment when compared to the same exercises on land (Alberton et al., 2015; Louder et al., 2019; Orselli & Duarte, 2011). Regarding water-based exercises usually employed in water fitness programmes, studies have observed Fz peak (Fzpeak) magnitudes ranging from ≈ 0.5 to 2.0 body weight in young individuals with normal weight at submaximal and maximal intensities (Alberton et al., 2015, 2013; De Brito Fontana et al., 2012, 2018; Fontana et al., 2015). These studies included water-based stationary exercises, such as running and kicking, and observed similar Fzpeak values between stationary running and frontal kick exercises due to their similar characteristics (Alberton et al., 2015, 2013). Thus, these water-based exercises may be safely prescribed for individuals who need to minimise the Fz (Alberton et al., 2013).
One-Phase and Two-Phase Flow in Highly Permeable Porous Media
Published in Heat Transfer Engineering, 2019
The result of the generalized Darcy’s laws does not agree with experimental data [87], [103]. This is illustrated in Figure 7, which represents the data obtained from experiments through a cylindrical porous column by [83], [104], as well as theoretical results. In these experiments, the column was initially saturated by water (β-phase), then gas (γ-phase) was injected from below. Liquid flowed out of the column from the top until a quasi-steady macro-scale situation was obtained. The figure shows the pressure gradient normalized by the liquid hydrostatic pressure gradient versus the gas velocity, for a liquid average velocity equal to zero. The simple generalized Darcy’s law models with Ergun’s type inertia term (Eq. (62)), as proposed by [105], [106], or [101], yield completely erroneous results. Below a critical velocity, the fluid is lifted by the gas and has a decreasing apparent weight. This corresponds to the viscous interactions, which in the model are captured by the term involving Kβγ. When the velocity is further increased, inertial effects, as taken into account in Eq. (61) by the extra term involving Fβγ, tend to reduce the lift and increase the apparent weight.
Evaluation of corrosion resistance of precast reinforced concrete subjected to early-age ambient pressure carbonation curing by accelerated impressed current method
Published in Journal of Sustainable Cement-Based Materials, 2023
Xiangping Xian, Duo Zhang, Yixin Shao, Shipeng Zhang
To evaluate the permeable porosity of concrete subjected to ambient pressure carbonation, water absorption was tested at 1 d and 28 d based on ASTM C642-13. The mass of the oven-dry sample was weighted as ma after drying in an oven for 72 h at 105 °C and cooling down to 23 °C. Then the sample was totally submerged in water for 48 h and subsequently boiled for another 5 h. After cooling overnight and removing the surface water content with paper towels, its mass at surface dry saturated condition was measured as mb. Lastly, the immersed apparent weight was recorded as mc by suspending the sample in water. |The water permeable porosity is calculated through Eq. 3.