On the Possibilities of Improving the Accuracy of the Evaluation of Inertia Forces in Laminar and Turbulent Films

The momentum equations for laminar and turbulent flow in fluid films are evaluated by assuming that the shape of the velocity profiles is not strongly affected by the presence of the inertia forces. Approximate integral momentum equations are thus obtained, which are similar in form to those proposed in a previous paper, but have an improved accuracy in evaluating the influence of the inertia forces, especially when the film exhibits regions with reverse flow. It is thus found that the overall influence of the inertia forces consists, for example, in a partial conversion of the static pressure into dynamic pressure when the flow is accelerated, rather than a complete conservation of the total pressure as assumed in a previous work.