Axial variations in geometry and presence of viscous displaced fluid are known to alter the diffusive-dynamics of capillary imbibition of a wetting liquid. We here show that the coupled effect of axially varying capillary geometry and finite viscosity of the displaced fluid can lead to significant variations in both short and long time dynamics of imbibition. Based on a theoretical model and lattice Boltzmann simulations, we analyze capillary displacement of a viscous liquid in straight and diverging capillaries. At short times, the imbibition length scales proportionally with time as opposed to the diffusive-dynamics of imbibition of a single wetting liquid. Whereas, at long times, geometry-dependent power-law behavior occurs which qualitatively resembles single liquid imbibition. The distance at which the crossover between these two regimes occurs depends strongly on the viscosities of the imbibing and the displaced liquid. Additionally, our simulations show that the early time imbibition dynamics are also affected by the dynamic contact angle of the meniscus.

This article elaborates a survey on water use events and activities in households. The survey inquires socioeconomic aspects, technology, processes and devices which may play an important role in these water use events. Processes like washing clothes and utensils, cooking refrigeration and heating are discussed. Devices like water purifiers, air-coolers, and toilets are qualitatively analyzed. Water use events such as bathing and brushing teeth are studied. The survey in online format and printed version was randomly responded by one hundred sixty people including fifty three family heads within city of Jodhpur, India. More than hundred respondents answered the online questionnaire from Mandi in north India, Delhi, the national capital territory and Jodhpur in west India. More than ninety per cent of the respondents were males. Climate of the regions mentioned above played a decisive role in water consumption. The general public was very much unaware of the policies of the government towards water conservation and management. Advertisements by vendors were found to misguide consumers providing importance to aesthetic features rather than technical specification. The implications of this study helps in becoming environmentally aware of how human actions affect the management of water and related energy use at households.

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