FLOW SIMULATION THROUGH A PIPE IN SOLIDWORKS

AIM: FLOW SIMULATION IN SOLIDWORKS

INTRODUCTION: SOLIDWORKS Flow Simulation is an intuitive Computational Fluid Dynamics (CFD) solution embedded within SOLIDWORKS 3D CAD that enables you to quickly and easily simulate liquid and gas flows through and around your designs to calculate product performance and capabilities.

Flow Simulation enables users to simulate a wide variety of liquids and gases for different engineering scenarios. A few common applications are flow through manifolds, heat exchangers, electronics cooling and aerodynamics.

REYNOLDS NUMBER – The Reynolds number (Re) is an important dimensionless quantity in fluid mechanics used to help predict flow patterns in different fluid flow situations. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow (eddy currents). These eddy currents begin to churn the flow, using up energy in the process, which for liquids increases the chances of cavitation. The Reynolds number has wide applications, ranging from liquid flow in a pipe to the passage of air over an aircraft wing. It is used to predict the transition from laminar to turbulent flow, and is used in the scaling of similar but different-sized flow situations, such as between an aircraft model in a wind tunnel and the full-size version.

GOVERNING EQUATIONS:

Reynolds Number –

`Re = (ρ×v×D)/μ`

where,

`ρ=`Density

`v=`Average Velocity at inlet

`D=`Equivalent Diameter / Hydraulic Diameter

`μ=`Dynamic Viscosity of fluid

GIVEN:

FLUID: Water

DENSITY: 1000 kg/m³

DYNAMIC VISCOSITY: 8.90 X 10^-4 Pa.s

LENGTH OF PIPE: 1 m

OUTER DIAMETER OF PIPE: 0.060 m

INNER DIAMETER OF PIPE: 0.058 m

THICKNESS: 0.002 m

INITIAL CONDITIONS:

At Re = 100

v = 0.00154 m/s

At Re = 1000

v = 0.0154 m/s

At Re = 10000

v – 0.154 m/s

PROCEDURE:

• A Pipe of required length is constructed in SolidWorks with Lids attached on both the sides to make it watertight. Generally, for performing CFD simulations, a watertight geometry is an essential feature that any object must possess, thereby constructing a computational domain. Line Probes are constructed at three positions including 85%, 90% & 95% of the length of pipe.

• In Flow Simulation tab, initial conditions using the Wizard option are assigned with flow type depending on the given conditions, i.e. Reynolds Number predicts the flow through pipe.

• The boundary conditions are specified with appropriate values followed by the discretization process. The mesh built is fine enough for satisfactory results.

• In the Feature Tree, XY Plot option is used for creating velocity plots at different positions of line probes.

• The Cut Plots are also assigned to the line probes for obtaining Normalized Velocity Contours. The maximum and minimum values should be taken as global maxima/minima or plot maxima/minima to obtain clear visual representations of the required results.

• A New parametric Study is run with input and output variables specified accordingly. The simulation is carried out and the results are obtained.

RESULTS:

• Re = 100

PROBE AT 95%

The Velocity at the boundaries is zero due to wall friction and the maximum value is attained at the diametral centre of pipe.

PROBE AT 90%

The profile is lesser developed at shorter lengths and thus show the transitioning into a fully developed flow.

PROBE AT 85%

In comparison to the line probe at 90% of the lrngth of pipe, the flow is less developed.

COMPARISON OF NORMALIZED VELOCITY PROFILES AT DIFFERENT LINE PROBE LOCATIONS

The Velocity Profile gets build up within shorter pipe length for low Reynolds Number. Also, farther from the inlet face, greater the velocity profile developed.

• Re = 1000

PROBE AT 95%

The above contour represent the boundary layer thickness which is smaller in comparison to the contours obtained with simulating flows at high Reynolds Number.

PROBE AT 90%

The above contour shows signs of lesser developed flow.

PROBE AT 85%

It shows the least development in comparison to the other line probe locations at a given Reynolds Number.

COMPARISON OF NORMALIZED VELOCITY PROFILES AT DIFFERENT LINE PROBE LOCATIONS

The Velocity profile is flattened due to under-developed flow. Line Probes at greater distance from the inlet face might show the fully developed flow.

• Re = 10000

PROBE AT 95%

The velocity close to the boundary possess some value, giving the perception of flow with highly undeveloped velocity profile.

PROBE AT 90%

The above contour represents the high velocty possessed by the fluid at line probe locations with very high reynolds Number.

PROBE AT 85%

The above contour represents the least developed flow in comparison to the above two contours for Re = 10000.

COMPARISON OF NORMALIZED VELOCITY PROFILES AT DIFFERENT LINE PROBE LOCATIONS

The transition to a fully develpoed flow is far off due to high velocities at inlet. The flow is highly flattened at the max velocity and the wall friction is getting overpowered by the momentum of fluid.

CONCLUSION: The Flow Simulation through a pipe is the basic interpretation of internal flow giving a thorough idea of basics of a CFD Simulation. We can conclude that with increased Reynolds Number, the velocity profile takes greater time to build and a longer pipe is desired for higher velocities to obtain satisfactory results.