The way you clean a flooded crawlspace depends on the type of flooding. If the crawlspace was flooded with concentrated sewage, you must remove the contaminated water and soil before you can do any other cleanup work. If you had overland flooding or groundwater seepage, remove the standing water and ventilate the crawlspace until the soil isn't muddy or overly damp. That reduces the chances of mold growth or structural damage.
Fans: The best way to dry the crawlspace is to place fans facing outward to draw the moist air out. Fans blowing into the crawlspace could force the moist air into the living space. Soils in crawlspaces may not dry completely. Cover the crawlspace floor with 6-mil polyethylene once the soil is no longer muddy. Ensure all seams are overlapped 6 inches and sealed or taped and that the polyethylene is attached and sealed extending up the crawlspace wall at least 6 inches.