Cold flow modeling generally refers to single component isothermal scaled physical experimental analysis of non-isothermal flow. Cold flow modeling is routinely performed for burners, boilers, flue gas ducts, air pollution control equipment, chimneys and petrochemical process equipment such as FCC (Fluidized Catalytic Cracker) units, cyclone separators, and reactors. While the non-isothermal flow in an actual unit may be qualitatively and quantitatively different from the cold flow model (depending upon the extent of the temperature range in the full scale unit), much can be learned about flow patterns and areas of concern for performance in the isothermal flow. When combined with 3D computational modeling, cold flow modeling is a valuable tool for detailed design.