Fluids rainfall

While some of these dynamics are natural, others are due to technological systems, or to cultural/social behavior or changes. While some of them can be described with high precision (e.g., fluid dynamics in a pipe or WWTP efficiencies), others can be approached (e.g., prevision of water demand) or estimated with low precision (e.g., rainfall regime of next years). 

The first and most critical step in developing a geochemical model is conceptualizing the system or process of interest in a useful manner. By system, we simply mean the portion of the universe that we decide is relevant. The composition of a closed system is fixed, but mass can enter and leave an open system. A system has an extent, which the modeler defines when he sets the amounts of fluid and mineral considered in the calculation. A system s extent might be a droplet of rainfall, the groundwater and sediments contained in a unit volume of an aquifer, or the world s oceans. 

To set up the calculation, we specify initial isotopic compositions for the fluid and calcite. We choose a value of —13 %c for r) 18 Os mow of the Lyons fluid, reflecting Tertiary rainfall in the region, and set the calcite composition to +11 %o, the mean of the measured values (Fig. 25.4). We further set S13C pi)B for the fluid to — 12 %o. We do not specify an initial carbon composition for the calcite, so the model sets this value to — 11 %c, in isotopic equilibrium with the fluid. Again, this value is near the mean of the measurements. 

Under certain conditions, ovulation and plasma gonadotropin levels can be stimulated by ovarian fluid from other ovulated females. The African catfish, Clariasgaricpinus, is an example. It lives in muddy water and spawns at night, conditions expected to favor pheromone commimication. Moreover, this species is a seasonal breeder, spawning after rainfall. The sudden mass spawning requires synchronization. Water from males or ovulated females, and also ovarian fluid of ovulated females, experimentally induced ovulation in 67% of females. Plasma gonadotropin was also increased by these treatments (Resink etal., 1989c). 

Even very solid roeks contain pores, and many of these pores are interconnected. It is through such pores that water and oil move toward wells. Below the water table, all the pores are filled with water with no surface tension to eliminate. So it might seem that rock down there would not be affected by rainfall at the surface. As the rains come, however, the water table rises, and the additional water increases the pressure in the fluids in the pores below. This increase in pore pressure pushes adjacent rock surfaces apart, reducing the friction between them, which lowers the strength of the rock and makes it easier for fractures to develop. Elevated pore pressures are implicated in many dramatic mass wasting events. 

Requires detailed rain chemistry studies including rainfall and vegetation throughfall measurements. -Typically uses washing of individual leaves and measurement of species concentration in wash fluid. 

Rainfall erosion experiment for gentle loess slope and fluid-soil coupling simulation with PFC ... 

The study of flow systems, which compose, of a porous medium and a homogenous fluid has attracted much attention since they occur in a wide range of the industrial and environmental applications. Examples of practical applications are flow past porous scaffolds in bioreactors, drying process, electronic cooling, ceramic processing, and overland flow during rainfall, and ground-water pollution. 

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