| 摘要 |
A urinal uses a sloped interior back wall to create a specific angle between an incoming urine stream and the back wall to effect an anti-splash phenomenon which involves the contact angle hysteresis and the coanda effect, thereby at least to minimize urine splashing. The contact angle hysteresis deals with the perpendicular angles at which the urine stream comes into contact with the back wall of the urinal bowl, that is the amount of angle degrees between the angle of surface of the bowl and the angle of the urine stream at the point of contact. This angle takes advantage of the Coanda effect so as to cause the fluid (urine) to run down the surface of the back wall to the bottom of the urinal, rather than splashing back. The Coanda effect is the tendency of a fluid jet to stay attached to an adjacent curved surface that is very well shaped. In one embodiment, the interior back wall is vertically sloped towards the user, at an angle greater than 20° from the vertical (e.g., 30° to accommodate a 60° urine stream), and the back wall may be further curved from side to side. In an other embodiment, the interior back wall has a undulated top-to-bottom or vertical contour.
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