This study deals with computational fluid dynamics (CFD) of fouling inside tubes or passages. These cases arise in present industrial situations involving fluid flows inside. The investigation on fouling is carried out by the technique called fluid dynamic gauging (FDG), which is a non-contact technique for measuring the thickness of soft deposit layer on solid surfaces immersed in liquid environment in situ and in real time. Laminar Newtonian flow has been investigated with Reynolds number at the nozzle throat in the range 116<Ret<930 and with the flow velocity of 0.0015 m/s to 0.124 m/s with water as the working fluid. The 3-dimensional model is created using SOLIDWORKS software. The fluid domain is discretized using finite volume method using ICEMCFD12.1 pre-processing tool. Both hexahedral and tetragonal mesh is generated which is used to capture the hydrodynamic boundary layers. The flow field through the 3-dimensional domain is captured by solving the appropriate governing equations namely conservation of mass and momentum equations. The convergence criteria are set to 10E-04 for mass and momentum. The numerically predicted results are compared with the experimental data available in the literature and a very good agreement exists between the two. Fouling phenomenon is calculated by finding the pressure difference between inlet and gauge tube outlet. © 2006-2014 Asian Research Publishing Network (ARPN).