Urinary bladder Urinary bladder The urinary bladder is a hollow muscular organ in humans and some other animals that collects and stores urine from the kidneys before disposal by urination. In the human the bladder is a hollow muscular, and distensible (or elastic) organ, that sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra. The typical human bladder will hold between 300 and (10.14 and ) before the urge to empty occurs, but can hold considerably more. In humans, the bladder is a hollow muscular organ situated at the base of the pelvis. Urine
Ludwieg tube Ludwieg tube A Ludwieg tube is a cheap and efficient way of producing supersonic flow. Mach numbers up to 4 in air are easily obtained without any additional heating of the flow. With heating, Mach numbers of up to 11 can be reached. A Ludwieg tube is a wind tunnel that produces supersonic flow for short periods of time. A large evacuated dump tank is separated from the downstream end of a convergent-divergent nozzle by a diaphragm or fast acting valve. The upstream end of the nozzle connects to a long cylindrical tube, whose cross-sectional area is significantly larger than