The Damkohler number is used in turbulent combustion and corresponds to the ratio of chemical time scale and turbulent time scale . This turbulent scale is usually taken as the integral scale.
Damkohler number measures how important is the interaction between chemistry and turbulence. Most combustion models are placed in the extremes of Damkohler.
If the turbulence is much faster than the chemistry. This regime is the "well-stirred reactor", where products and reactants are rapidly mixed. The Karlovitz number is linked to the Damkholer number.
The Damkohler number is also defined in a chemical non-equilibrium process at very high velocities of the fluid or vehicles (with reference to fluid). There are two ratios of Damkohler number that can be defined and are as follows:
1. First Damkohler Number or DAM 1
Where is the residence time of the flow, where where is the reference length of the vehicle and is the reference velocity of fluid or vehicle with respect to fluid
2. Second Damkohler Number or DAM 2
Where is the energy involved in a non-equilibrium process and is the total enthalpy of the flow