scholarly journals Water droplet dynamics on bioinspired conical surfaces

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190118 ◽  
Author(s):  
Charles T. Schriner ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
High Water ◽  
Laplace Pressure ◽  
Conical Surface ◽  
Human Consumption ◽  
Droplet Dynamics ◽  
Water Collection ◽  
Droplet Movement ◽  
Movement Distance ◽  
Conical Surfaces

Cacti use the Laplace pressure gradient due to conical geometry as a mechanism for collecting water from fog. Bioinspired surfaces using conical geometry can be developed for water collection from fog for human consumption. A systematic study is presented which investigates the dynamics of water droplets on a bioinspired conical surface. A series of experiments was conducted where a known volume of droplets was deposited on the cone. This was followed by an investigation into droplet dynamics where the droplets are deposited from fog and the volume is unknown. This includes a study on the macroscopic level as well as the microscopic level. The main parameters that were varied for these tests were the tip angle and the cone orientation. The droplet movement observed was compared relatively. Based on captured videos of droplet movement, distance travelled and velocities were measured. The Laplace pressure gradient, gravity and droplet coalescence were found to be the mechanisms of droplet movement on a conical surface. The findings of this study should be of interest in designing bioinspired surfaces with high water collection. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals Optimization of bioinspired triangular patterns for water condensation and transport

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190127 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Relative Humidity ◽  
Pressure Gradient ◽  
Surface Temperature ◽  
Dew Point ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Water Condensation ◽  
Water Collection ◽  
Condensed Water ◽  
Droplet Condensation

Water condenses on a surface in ambient environment if the surface temperature is below the dew point. For water collection, droplets should be transported to storage before the condensed water evaporates. In this study, Laplace pressure gradient inspired by conical spines of cactus plants is used to facilitate the transport of water condensed in a triangular pattern to the storage. Droplet condensation, transportation and water collection rate within the bioinspired hydrophilic triangular patterns with various lengths and included angles, surrounded by superhydrophobic regions, were explored. The effect of relative humidity was also explored. This bioinspired technique can be used to develop efficient water collection systems. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals Bioinspired triangular patterns for water collection from fog

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190128 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
Science And Technology ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Droplet Motion ◽  
Triangular Shape ◽  
Conical Shape ◽  
Bioinspired Materials ◽  
Water Collection ◽  
Curvature Gradient

Cacti use spines with conical geometry to transport water to its base. A conical shape with curvature gradient generates a Laplace pressure gradient along the droplet, which is responsible for droplet motion. In this study, the triangular shape was used which also generates a Laplace pressure gradient along the droplet. A bioinspired surface, composed of a hydrophilic triangular pattern surrounded by a rim of superhydrophobic region, was used to transport water collected from the fog on the hydrophilic pattern. The growing droplets start to coalesce into bigger ones. Eventually, they are big enough to touch the superhydrophobic borders, which trigger the transport motion. Droplet mobility and water collection measurements were made on triangular patterns with various geometries to determine the most efficient configurations. Results from this study can be used to enhance the performance of water collection systems from fog. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals Bioinspired conical design for efficient water collection from fog

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190125 ◽  
Author(s):  
Dev Gurera ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
Laplace Pressure ◽  
Surface Slope ◽  
Water Droplets ◽  
Theme Issue ◽  
Conical Shape ◽  
Gravitational Forces ◽  
Water Collection ◽  
Curvature Gradient ◽  
First Time

Nature is known for using conical shapes to transport the collected water from fog for consumption or storage. The curvature gradient of the conical shape creates a Laplace pressure gradient in the water droplets which drives them towards the region of lower curvature. Linear cones with linearly increasing radii have been studied extensively. A smaller tip angle cone transports water droplets farther because of higher Laplace pressure gradient. Whereas a larger tip angle with a larger surface slope transports water droplets because of higher gravitational forces. In this study, for the first time, a nonlinear cone with a concave profile has been designed with small tip angle and nonlinearly increasing radius to maximize water collection. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

Optimizing Water Harvesting on Bioinspired Surfaces: A Mesoscopic Perspective

2021 ◽  
Author(s):  
Souparna Chakraborty ◽  
Abhirup Chaudhuri ◽  
Chirodeep Bakli
Keyword(s):  
Pressure Gradient ◽  
Water Transport ◽  
Tilt Angle ◽  
Transport Process ◽  
Collection Efficiency ◽  
Md Simulations ◽  
Laplace Pressure ◽  
Water Harvesting ◽  
Collection Rate ◽  
Water Collection

Abstract The water crisis affects the lives of millions over the world. Minimizing water losses in major water-consuming industries like power plants is of utmost importance. Since cooling towers lead to huge amounts of water loss, implementing modifications for recovering a fraction of this lost water in the exhaust has been a topic of active research. These modifications are often inspired by biological species, especially in arid regions, which have adapted in different ways by collecting water from fog, and hence biomimetic has become popular for water harvesting techniques. We revisit the fog collection technique most commonly used in nature and compare the relative merits of the same with surface texture and wettability. Arrays of spines of three different configurations were considered in this study — namely cuboidal, cylindrical and conical shapes. A theoretical model is developed to carry out a comparative analysis of these configurations considered. The effects of Laplace pressure gradient, gravity, topography and tilt angle on droplet transportation along the spines were explored to decipher the most efficient water transport and collection route. The observations are explained by performing extensive Molecular Dynamics (MD) simulations to bring out the interplay of surface tension and roughness at the contact line verifying the proposed formulations. The conical-shaped spines exhibited maximum transport and collection efficiency for zero tilt angle. Both cuboidal and cylindrical shaped spines showed little or no water collection when the spines are oriented horizontally. This is due to the Laplace pressure gradient which arises from varying radii of curvature of the conical shaped spine which drives the water droplets towards the base but is absent for the other two cases considered. On the contrary, when there is some finite tilt angle, the contribution of gravity comes into consideration and the water collection rate of the conical and cylindrical spines becomes comparable. Both Laplace pressure gradient and gravity help in water transport in the conical case whereas only gravity assists the water transport process for cylindrical spines. Still, the water collection rate is almost the same for these two scenarios due to enhanced coalescence of liquid droplets for the cylindrical case as is observed from MD simulations. As the droplets coalesce, they get larger and gravity aids the transport process by overcoming the solid-liquid interaction strength. Cuboidal shaped spines show the least efficiency with only gravity to assist the transport process and no coalescence is observed in this case. Moreover, the geometrical disparity makes the tips of conical spines more hydrophobic compared to the others which further ameliorates the water collection efficiency.

scholarly journals Identifying Problems in Watering Ponds with Different Purposes

Environments ◽  
2020 ◽  
Vol 7 (9) ◽  
pp. 63
Author(s):  
Manuel Pulido ◽  
Alberto Alfonso-Torreño ◽  
Jesús Barrena-González ◽  
Rafael Robina-Ramírez ◽  
Mohamed Amine Abdennour
Keyword(s):  
Fish Farming ◽  
High Water ◽  
Water Shortage ◽  
Quality Parameters ◽  
Mitigation Strategies ◽  
Fecal Coliforms ◽  
Human Consumption ◽  
Subtropical Climate ◽  
Livestock Farming ◽  
Azolla Filiculoides

The main goal of this study was to identify the problems that are putting the viability of watering ponds at risk. For doing that, we have analyzed five different study cases: (I) livestock consumption, Mediterranean climate (rangelands of SW Spain), (II) multifunctional ponds (Arroyo de la Luz, Spain), (III) ecotourism (Valdepajares de Tajo, Spain), (IV) crop irrigation and fish farming, semi-arid climate (the wilaya of Ouargla, Algeria), and (V) livestock consumption, humid subtropical climate (Prudentópolis, Brazil). The identification of problems was made through surveys, personal interviews, local knowledge and literature review as well as through the analysis of water quality parameters such as the concentration of phosphates and fecal coliforms in some ponds. We have identified problems of water shortage (ca. 50% of rangeland farmers), pollution induced by agriculture (maximum values of phosphates = 1.33 mg L−1) and livestock farming (maximum value of fecal coliforms ≈ 7000 cfu mL−1), low potability for human consumption (score: 2.8/7.0), invasive species such as Azolla filiculoides (10 out of 17 watering ponds), high water temperature for aquaculture in summer (Algeria) and the increase of turbidity in nearby water courses due to the actions of free-fattening pigs (Brazil), among many other problems. We conclude an extra effort by stakeholders is still needed in order to agree mitigation strategies.

scholarly journals Designing bioinspired surfaces for water collection from fog

2018 ◽  
Vol 377 (2138) ◽  
pp. 20180269 ◽  
Author(s):  
Dev Gurera ◽  
Bharat Bhushan
Keyword(s):  
Flat Surface ◽  
Unit Area ◽  
Water Repellency ◽  
Vertical Axis ◽  
Collection Rate ◽  
Flat Surfaces ◽  
Single Cone ◽  
Water Collection ◽  
The Difference ◽  
Conical Surfaces

A systematic study is presented on various water collectors, bioinspired by desert beetles, desert grass and cacti. Three water collecting mechanisms including heterogeneous wettability, grooved surfaces, and Laplace pressure gradient, were investigated on flat, cylindrical, conical surfaces, and conical array. It is found that higher water repellency in flat surfaces results in higher water collection rate and inclination angle (with respect to the vertical axis) has little effect. Surfaces with heterogeneous wettability have higher water collection rate than surfaces with homogeneous wettability. Both cylindrical and conical surfaces resulted in comparable water collection rate. However, only the cone transported the water droplets to its base. Heterogeneity, higher inclination and grooves increased the water collection rate. A cone has a higher collection rate per unit area than a flat surface with the same wettability. An array of cones has higher collection rate per unit area than a single cone, because droplets in a conical array coalesce, leading to higher frequency of droplets falling. Adding heterogeneity further increases the difference. Based on the findings, scaled-up designs of beetle-, grass- and cactus-inspired surfaces and nets are presented. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology’.

The utilization of fish by-products and waste in animal feeding

1980 ◽  
Vol 3 ◽  
pp. 85-90 ◽  
Author(s):  
I. H. Pike ◽  
I. N. Tatterson
Keyword(s):  
Fish Oil ◽  
Fish Meal ◽  
High Water ◽  
High Water Content ◽  
Human Consumption ◽  
Chemical Changes ◽  
Lean Fish ◽  
Bacterial Action ◽  
Animal Feeding ◽  
By Products

Most of the by-products from fish go into the production of fish meal and fish oil, the latter going directly to the human food chain, and therefore do not really come under the heading of industrial by-products and waste per se. Broadly speaking, fish meal made from fish offal is a by-product which otherwise would have been wasted. This paper discusses the quantities involved and the nutritional properties offish meal, and in addition, the contribution to fish meal and fish oil made from species which are not suitable for human consumption (e.g. sandeels) or where the quantities caught exceed the demand for human consumption (e.g. sprats).Any method of utilizing fish by-products for animal feeding should minimize chemical changes in the product to avoid reduction in the nutrients which are present at the time of catching. In some respects chemical changes in fish by-products are brought about in a similar way to those in grass, cut for preservation. The fish material has a high water content, around 75%, and from the time of catching is subject to chemical changes by enzymes in the fish and also by bacterial action. Fish, however, differs from grass in that it contains oil and virtually no carbohydrates. The demersal, or lean fish, for example, cod, haddock, plaice, saithe, etc., contain high levels of oil in the liver which are removed for separate processing, but little in the flesh and in the offal produced. The ‘industrial’ fish caught are mainly pelagic species with high levels of oil in the flesh.

scholarly journals Oilseed Cake Flour Composition, Functional Properties and Antioxidant Potential as Effects of Sieving and Species Differences

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2766
Author(s):  
Jan Bárta ◽  
Veronika Bártová ◽  
Markéta Jarošová ◽  
Josef Švajner ◽  
Pavel Smetana ◽  
...  
Keyword(s):  
Functional Properties ◽  
Crude Protein ◽  
Antioxidant Activities ◽  
High Water ◽  
Human Consumption ◽  
Milk Thistle ◽  
Sds Page ◽  
Oilseed Cake ◽  
Water Holding ◽  
As Effects

Oilseed cakes are produced as a by-product of oil pressing and are mostly used as feed. Their use for human consumption is due to the functional properties and benefits for human health. Herein, oilseed cake flours of eight species (flax, hemp, milk thistle, poppy, pumpkin, rapeseed, safflower, sunflower) were sieved into fractions above (A250) and below (B250) 250 µm. The chemical composition, SDS-PAGE profiles, colour, functional properties and antioxidant activities of these flours were evaluated. The B250 fractions were evaluated as being protein and ash rich, reaching crude protein and ash content ranging from 31.78% (milk thistle) to 57.47% (pumpkin) and from 5.0% (flax) to 11.19% (poppy), respectively. A high content of carbohydrates was found in the flours of hemp, milk thistle and safflower with a significant increase for the A250 fraction, with a subsequent relation to a high water holding capacity (WHC) for the A250 fraction (flax, poppy, pumpkin and sunflower). The A250 milk thistle flour was found to have the richest in polyphenols content (TPC) (40.89 mg GAE/g), with the highest antioxidant activity using an ABTS•+ assay (101.95 mg AAE/g). The A250 fraction for all the species exhibited lower lightness than the B250 fraction. The obtained results indicate that sieving oilseed flour with the aim to prepare flours with specific functional characteristics and composition is efficient only in combination with a particular species.

Directed motion of water droplets on multi-gradient photopolymer surfaces

2019 ◽  
Vol 10 (15) ◽  
pp. 1882-1893 ◽  
Author(s):  
E. Rossegger ◽  
D. Hennen ◽  
T. Griesser ◽  
I. Roppolo ◽  
S. Schlögl
Keyword(s):  
Pressure Gradient ◽  
Laplace Pressure ◽  
Water Droplets ◽  
Directed Motion ◽  
Directional Movement

Rapid and directional movement of water droplets across a photopolymer surface with inscribed wettability and Laplace pressure gradient is demonstrated.

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