In order to set the context for the modeling of turbulent flow it is essential to
understand why turbulent flow simulations are challenging.
First, examine the turbulence characteristic non-repetition. Figure 1 shows two snapshots of smoke
plumes from a burning incense stick. Both instantaneous plumes show the chaotic,
continuously evolving movement of the smoke. Due to the sensitivity of the smoke plumes to
surrounding conditions (temperature, density and cross flow velocity), the pattern of their
movement never repeats. Thus, prediction on such instantaneous turbulent smoke evolutions is
understood to be quite challenging. Figure 1. Snapshots of Smoke Plumes
