Thermal Anemometer is a simple instrument used to measure the velocity of gases, both for contained flow (airflow in a duct) or unconfined flow (atmospheric wind). A few industries use this instrument for certain liquids, too, by checking on specific physical properties of the liquid or the effect of fluid on the inserted mechanical device.
In general, the common application of an anemometer measures the speed of gases or liquids, mainly for turbulent flow. In most cases, the instrument helps measure the mean velocity. Generally, the thermal anemometer refers to a gadget version that works on the relation between heat transfer and speed to determine the speed.
A thermal anemometer uses an excellent wire or an element to heat up to a specific temperature. The hot-wire device can be classified into CCA (Constant current anemometer), CVA (constant voltage anemometer) and CTA (Constant temperature anemometer).