Special consideration must be given to one detail in order to compare the heat transport associated with bolus flow to that associated with the Poiseuille flow. As will appear, when bolus flow is produced in the model the boluses of liquid are separated from one another by boluses of air. The heat transported by the may safely be neglected, so that only a fraction, say J of the total fluid (air plus water) is transporting heat. This complicating factor may be taken into account by defining an “idealized bolus flow” in which the velocity profile across the bolus is parabolic; i.e., of the Poiseuille type. In any given case the J and average velocity associated with the idealize bolus flow ( ) will be identical with those of the actual bolus flow. The heat transfer coefficient associated with this idealize bolus flow may be calculated from parametric equation :