Image made using the COMSOL Multiphysics® software and is provided courtesy of COMSOL.
Cooling of a steering wheel injection mold: Non-isothermal pipe flow is fully coupled to the heat transfer simulation of the mold and polyurethane part.
The Pipe Flow Module is used for simulations of fluid flow, heat and mass transfer, hydraulic transients, and acoustics in pipe and channel networks. It can be easily integrated with any of the other modules in the COMSOL® Product Suite for modeling the effects piping has on larger entities, such as cooling pipes in engine blocks or feeding and product channels connected to vessels. This allows for the conservation of computational resources in your overall modeling of processes that consist of piping networks, while still allowing you to consider a full description of your process variables within these networks. Pipe flow simulations provide the velocity, pressure, material concentrations, and temperature distributions along pipes and channels, while it can also simulate acoustic wave propagation and the water hammer effect.
The Pipe Flow Module is suitable for modeling incompressible flow in pipes and channels whose lengths are large enough that flow can be considered fully developed. With this assumption it uses edge elements, solving for the tangential cross-section averaged velocity along the edges, to avoid meshing the cross section of the pipe with a full 3D mesh. This means that the modeled variables are averaged in the pipe’s cross sections and vary only along the length of the pipe. Built-in expressions for Darcy friction factors cover the entire flow regime including laminar and turbulent flow, Newtonian and non-Newtonian fluids, different cross-sectional shapes or geometries, and a wide range of relative surface roughness values. These can be varied according to their position in the network, or directly related to the variables you are modeling.
Friction is not the only contribution to pressure loss in pipe networks. The Pipe Flow Module also considers the effects of bends, contractions, expansions, T-junctions, and valves that are computed through an extensive library of industry standard loss coefficients, while pumps are also available as flow-inducing devices. As with any physics interface in the COMSOL Product Suite, you can freely manipulate the underlying equations, add your own source or sink terms, and express physical property as functions of any model variable. COMSOL Multiphysics® also allows you to bring in data to describe a certain material property or process parameter, as well as subroutines written in MATLAB®.
* Requires the Acoustics Module.
This model shows how you can use the Non-Isothermal Pipe Flow interface together with the Heat Transfer in Solids interface to model the cooling of a injection molded polyurethane part for a car steering wheel.
The equations describing the cooling channels are fully coupled to the heat transfer equations of the mold and the polyurethane part.
This example models flow in a microchannel heat exchanger by coupling a Laminar Flow interface in 3D to a Pipe Flow interface. By the use of the Pipe Flow interface to model the flow in the microchannels the problem size is significantly reduced.
This model showcases the Pipe Connection feature that automatically connects a 3D and and Pipe Flow domain.
It is often not possible to insert a normal microphone directly into the sound field being measured. The microphone may be too big to fit inside the measured system, such as for in-the-ear measurements for hearing aid fitting. The size of the microphone may also be too large compared to the wavelength, so that it disturbs the acoustic field. In these cases, a probe tube may be attached to the microphone case in order to distance the microphone from the measurement point. In this model, the effect on the microphone’s sensitivity due to the addition of this small probe will be investigated.
This is a time-dependent model of a generic probe tube microphone setup consisting of an external acoustic domain, an elastic probe tube, and the cavity in front of the microphone diaphragm. The probe tube, modeled using the Pipe Acoustics, Transient physics interface, is connected to two separate 3D pressure acoustics domains, leading to a fully coupled acoustics simulation. This model requires the Pipe Flow Module.
The Organ Pipe Designer allows you to study the design of an organ pipe and then play the sound and pitch of the changed design in a user-friendly app. The pipe sound includes the effects of different harmonics with different amplitudes.
The organ pipe is modeled using the Pipe Acoustics, Frequency Domain interface in COMSOL Multiphysics. The simulation app allows you to analyze how the first fundamental resonance frequency varies with the pipe radius and wall thickness, as well as with the ambient pressure and temperature.
Using the app, you can find the full frequency response, including the fundamental frequency and the harmonics. With a Java® code written method, the app will detect the location and amplitude of all harmonics in the response, thus extending the analysis beyond the built-in functionality of the COMSOL Multiphysics user interface.
Ponds and lakes can serve as thermal reservoirs in geothermal heating applications. In this example, fluid circulates underwater through polyethylene piping in a closed system. The pipes are coiled in a slinky shape and grouped onto sleds. The Non-isothermal Pipe Flow interface sets up and solves the equations for the temperature and fluid flow in the pipe system, where the geometry is represented by lines in 3D.
As oil flows through a pipeline section heat is released due to the work of internal friction forces in the fluid. With good insulation of the pipeline, this generated heat can be used to avoid preheating of the oil, despite the fact that it is to be transported in a cold environment over long distances.
This model uses the Non-isothermal Pipe Flow interface to set up and solve the flow and energy equations describing oil transport in a pipeline section. With the addition of an Optimization interface, the thickness of the pipeline insulation can be found such that the temperature is constant throughout the pipe.
This tutorial model illustrates how to calculate the pressure drop and initial flow rate in a pipe system connected to water tank. The Pipe Flow interface contains ready to use friction models accounting for the surface roughness of pipes as well as pressure losses in bends and valves.
When a valve is closed rapidly in a pipe network it gives rise to a hydraulic transient known as a water hammer. The propagation of these hydraulic transients can in extreme cases cause failures of pipe systems caused by overpressures. This is a model of a simple verification pipe system consisting of a reservoir, a pipe, and a valve. The valve is in this model closed instantaneously.