The wire can be located upstream locations of the test model. The tunnel must be ventilated to remove the smoke from its closed circuit, if extensive use is required. The other flow visualization methods are applied on the model surface during wind-off conditions. The oil, China clay and sublimation methods are based on various kinds of mixtures. They are applied on the model surface, and slugged down in the direction of air, making the flow character visible when the air is turned-off.
Tufts are easy to use and clean for wind-on flow visualization.
They are made of thread and attached to the model surface in successive rows. As the air is turned on, the tufts flap in the flow direction. The tunnel has photographic equipment to record testing. A digital camera is used for taking the pictures and viewing them on computer in a sequence. A high-speed VHS video camera is available for recording active flow visualization or other phases of testing.