Zones vertical down flow

A closer look at the zone of vertical downflow paths. Local recharge flows vertically down until the zone of lateral flow is reached. In coastal plains the vertical flow zone is fairly thin, on the order of a few meters to a few tens of meters, and it clearly coincides with the aerated zone, and the water table signifies the zone of lateral base flow. In mountainous regions the vertical flow paths are longer, and usually the higher the topographic relief is, the thicker is the zone of vertical downflow. The following observations testify to the existence of vertical downflow paths ... 

Mountain slopes and escarpments are often with no springs, although they are recharged by precipitation. This is a clear indication that in such regions the recharge water flows vertically down until it meets a lateral flow zone at greater depth (Fig. 2.15). 

One of the causes of aerosol increase in the atmosphere is the radioactive burst in the epicenter of underground nuclear explosions. If after an explosion, the aerosol cloud gets into the zone of jet flow, it will settle down or rise up depending on the leg it encountered (anticyclone or cyclone). The higher the wind velocity in the jet is, the higher the layer of maximum values of aerosol concentrations is located. The upward aerosol transfer on a cyclone leg is more intensive than the downward transfer on an anti-cyclone leg, as the ascending vertical velocities are more powerful than the descending ones. 

The flow field created within the protection zone depends mainly on the density difference between supply air and room air (Fig. 10.90). With vertical flow the supply air should be isothermal or cooler than ambient air. If it were warmer, the extension of the controlled flow would be reduced due to buoyancy effects, resulting in the supply air not reaching the operator s breathing zone. As the. supply air cannot be used for heating, the operator s thermal comfort should be maintained, preferably with radiant heaters in cold environments. If the supply air temperature is lower than the room air, the denser supply air accelerates down to the operator, and for continuity reasons the supply flow contracts. Excessive temperature differences result in a reduced controlled flow area with thermal discomfort, and should only be used in special cases. 

Procedure, ioo c.c. of the wine are evaporated in a flask to io c.c., allowed to cool and treated with 6 c.c. of the saturated ferrous sulphate solution and 4 c.c. of concentrated sulphuric acid.1 The flask is connected with a vertical condenser about 50 cm. long and heated carefully over a small flame so that excessive frothing of the mass is avoided. The distillate is collected in two or three well-cleaned tubes, each containing 2-3 c.c. of the iodide-starch paste acidified with 2 drops of dilute sulphuric acid the tubes are inclined so that the distillate flows down the walls. In presence of nitrites, a blue ring forms at the zone of separation between the starch and the distillate. 

A horizontal air stream entering this zone expands within a chamber and converges towards the outlet (Fig. lb). Particles fed in the chamber with zero velocity accelerate horizontally by the drag force Fd and also fall down. At the end of the acceleration interval the horizontal velocity component vx of all particles almost reaches the are flow velocity u and they do not separate in this direction. Separation occurs due do particles vertical motion across the air stream. Each particle falls at its own terminal settling velocity. Accordingly, due to the horizontal motion they land on the bottom at different chamber locations coarse-close to the inlet, smaller-close to the outlet. Coarse fraction is gathered on the bottom of the chamber, fines do not reach the bottom and are carried away by the air flow through the outlet. 

---