COMPUTATIONAL FLUID DYNAMIC ANAYLSIS OF A MULTI-PHASE FLOW DURING INHALATION THERAPY USING DRY POWDER INHALERS

Project Overview

·         A typical metered dose inhaler (as shown in fig. 3) consists of propellants, drug formulation, metering valve, and actuator. Propellants in inhalers are liquefied compressed gases that are in the gaseous phase at atmospheric pressure, but form liquids when compressed. While drugs in M.D.I.s take the form of either particulate suspensions or solutions. For the scope of analysis, we have assumed the formulation to be in form of a particulate suspension while propellants to be in gaseous states. Hence our fluid is a mixture of gas and solid particulate.

·         Propellants normally used in DPIs have  with molecular mass of approx. 137 gm/mol & density of 41.49 g/cm³ are generally used, while we assume properties of Salbutamol (i.e. approx. molecular mass: 239.31 g/mol & density 0.1 g/cm³) for the formulation particulate.

·         Formulation particulates have diameters spanning from 1-12µm, hence we have selected 10µm as the R.M.S. value for analysis.

·         Assumed that there is no slip condition of the fluid inside the airways.

·         There is a one way coupling between fluid and solid.