October 2018 | Matrix Technologies Incorporated

Computational Fluid Dynamics: Solving Problems with Fluid Flows

What is Computational Fluid Dynamics?

When designing a piece of equipment or designing a processing system that involves liquids or gasses, it is often difficult to assess exact specifications without knowing how those liquids and gasses will behave. In these cases where fluid behavior is a major factor in design, an understanding of fluid mechanics—the analysis of how fluids behave in response to forces exerted upon them—is crucial. While testing a virtual prototype utilizing computational fluid dynamics, engineers can analyze: the turbulence in fluid as it flows, force exerted on equipment by gasses, possibilities of changes in state, dispersion, ill effects, cavitation and more.

The stock definition of computational fluid dynamics (CFD) is: a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyze problems that involve fluid flows. To truly make use of this data, engineers employ their knowledge of computational fluid dynamics, and couple the results with physics, industry best practices, operational knowledge or other data to simulate a real world scenario and determine if a course of action or a design is acceptable or unacceptable. CFD allows engineers to predict fluid response in different situations and create simulations to test their predictions. Changing the variables and studying the simulation results can help engineers find the optimal design based on fluid flow.

How Do Engineers Put CFD to Work?

The process of CFD is multi-faceted. First, the engineers determine the total volume of the fluid or gas to be measured. In order to analyze the problem, however, the larger volume must be broken down into manageable pieces. To accomplish this breakdown, engineers use a process called meshing to create a control volume to improve the accuracy of calculations.

Emergency Building Ventilation Volume Render with Miniscule Control Volumes

As you can see in the illustration above, meshing takes a large volume of a liquid or gas and breaks it down into discrete sub-elements, or control volumes; for example, this process could break down the complete volume of a liquid in a 30’ long x 10” dia. pipe into a million sub-elements. Discretizing the liquid in this way creates a control volume that can be used to calculate fluid behaviors more precisely. This can be thought of as breaking down the volume into very small pieces so that fluid flow can be simulated as it would occur in reality.

Once the meshing is complete, boundary conditions can be put in place and a three-dimensional model can be built for simulations. The engineers will then use this physical model to simulate how a liquid or gas will behave in response to changes in temperature, turbulence, and obstruction, among other conditions. An example of this could be that an oil refinery has a butterfly valve whose body deteriorates over time. The valve can be modeled 3 dimensionally and the hydrocarbon stream flow can be simulated through the valve to gather necessary data to determine root cause of valve failure.

Because the CFD process is so complex, engineers use powerful CFD software, such as Ansys Mechanical CFD (which we use at Matrix). This software allows us to complete the complicated process of defining the problem, creating the mesh, and designing the model. Once our engineers run simulations, this software also completes complicated mathematical equations quickly to help solve the problems and analyze the efficacy of potential solutions.

When is Computational Fluid Dynamics Useful?

There are many situations in which CFD can be useful, but determining whether to use it is more often a decision regarding cost-effectiveness. The use of CFD is always a question of scale: it’s usually most useful where traditional methods and “go-bys” have already proven to be ineffective.

High Velocity Air Inlet and Flow Straightener Simulation

Some examples of problems that Matrix has solved using CFD include:

A company in the oil, gas, & chemical industry wanted to have an emergency process in place in the event of an ammonia loss of containment. Matrix, through CFD simulation, determined how quickly the client could reduce the amount of ammonia in the air to make it safe for workers to re-enter the building by modeling portions of the facility and simulating a dispersing ammonia cloud in air.
Another company in the oil, gas, & chemical industry employed a process that needed to cool a gas from 3000°F to 1000°F within a 5 feet run of pipe. Matrix used CFD to simulate flow and design a quenching process (water spray) that dispersed at a specific time and flow to accomplish that precise process.
A company in the oil & gas industry was working with a substance that would begin to solidify into lumps below a certain temperature. Matrix used a CFD analysis to pinpoint places where the substance would be most likely clump and clog pipes. After the analysis determined potential problem areas, Matrix was able to provide the client with a revised piping design that limited potential for clogging.

CFD can also be very useful to analyze the cause of and provide solutions for water hammer in all liquid flow processes. Water hammer can be a very powerful and damaging force. (You can read more about water hammer in food and beverage applications here: http://matrixti.com/?s=water+hammer . In essence, any process that requires careful analysis or simulation of liquid and gas behaviors can benefit from CFD.

The Benefits of CFD

As you can see from our description of the processes involved with CFD, trying to solve complicated fluid dynamics problems without CFD methods and software can be next to impossible. When presented with a large-scale, complex fluid flow problem, engaging engineers to employ a CFD process can be crucial. CFD can solve many pain points in liquid or gaseous flow issues, including heat transfer simulation, changing fluid properties, cavitation, chemical leaks, water hammer, material pitting or abrasion, flow induced vibration and countless other fluid scenarios. To put it in summary: if there is a potential for a flow induced pitfall or a new design requires the insight of fluid flow simulation, CFD can be the answer.

Matrix Technologies is one of the largest independent process design, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about Computational Fluid Dynamics and Multidiscipline Engineering, contact Chris Mach, PE, Senior Consultant (Team Leader), Process Solutions Department.

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Matrix Engineers Turn Old Warehouse into Modern Manufacturing Facility

For any engineering project, understanding the arrangement of the building, equipment, and space is very important. In a typical industrial greenfield project, the focus is on the process and packaging aspects. Once these are defined, the building and its features are laid-in to accommodate this process and packaging footprint. Building structural members, utilities locations, office spaces, and ancillary facilities are positioned in a fashion to provide the optimal performance of the facility while keeping in mind accessibility, utilities, material flow, and ergonomics.

In contrast, with a brownfield site, the owner and engineer are at the mercy of the existing building and its features. Because of this, the process must be reverse-engineered to fit into the available space. This can often become a difficult task, especially in older facilities if existing drawings are not available. This was the case with a recent project that Matrix Technologies completed for a customer in the southeast area. Our engineers were tasked with turning a 250,000 ft² brownfield site (built in the 1950s) into a functional facility to accommodate a new manufacturing process that consisted of raw material storage, batching, filling, and packaging.

Project Phases

Matrix approached the project in three phases: scanning, demolition, and engineering.

Phase One: Scanning

During the first phase of the project, Matrix engineers laser scanned the existing facility to define the building and internal features. With this data, Matrix was able to generate a 3D model of the existing building, which was shared with the equipment vendor responsible for the packaging equipment. Once the final layouts were reviewed and approved by the owner, the second phase of the project could commence.

Phase Two: Demolition

Several abandoned areas of the building required demolition and refurbishment before the space could accommodate the new process. During phase two, our team developed demolition plans for removing existing walls, slabs, office spaces, restrooms, and site features that were necessary to accommodate the new process infrastructure.

Phase Three: Engineering

The Matrix team worked very closely with the owner on the engineering package development, focusing efforts on long-lead items such as tanks specs, pumps, valving, and instrumentation, as well as areas of the facility requiring significant construction efforts. The packages were broken down into (1) architectural, (2) civil/site, (3) process/mechanical/piping, (4) power/instrumentation/controls, and (5) programming.

Architectural Design. Matrix’s team worked very closely with the customer team to arrange the facility to meet the functionality of the process, incorporating multiple vendor equipment layouts and the proposed facility modifications. They also ensured their designs met the requirements of local and state building codes.

The team was also responsible for the design of a new 7,000 ft² office space. Because the existing office area was not functional for the needs of the customer, our team developed plans for demolishing the existing space and designing a new floor plan that incorporated several new offices, conference rooms, locker rooms, cafeteria/breakroom, control room/lab space, plant floor restrooms, shift change conference room, upgraded shipping and receiving offices, and a flammable storage room.

Civil/Site Design. For this phase of the project, the site had to be redeveloped to accommodate a new tanker truck unloading station. Our team faced two significant challenges: (1) several elevation changes from the road entrance to the building and (2) multiple drainage problems that led to water pooling in the proposed unloading area. In order to combat the elevation changes, significant grading of the site was completed to allow for the truck access and maneuverability. To handle the drainage issues, our team installed new trench drains at the apron of the drive access points with a secondary trench drain expanding the width of the trucking unloading area. Whatever remaining water that was not caught by the drains was directed to a catch basin that ties into the main city storm system. Since the installation, no pooling or flooding has been observed onsite.

In addition to the truck unloading area, a new employee parking lot was engineered and constructed on the site. Existing green space in front of the office was utilized for the new 60-space lot which included new lighting, security fencing, access gates, and turnstiles. Due to the acreage disturbed, a new retention pond was installed to meter the storm runoff into the city storm system.

Process/Piping/Mechanical Design. The process design for the project revolved around raw material transfer, storage, and batching. Matrix’s process and piping engineers developed the P&IDs with the customer team and used its 3D modeling software along with the point cloud to engineer the interconnecting piping between the raw material tanks, batch tank, flammable storage room, and filler. The Matrix team also developed tank and mechanical equipment specifications and aided the customer by vetting bids and making recommendations for the purchase of tank and mechanical equipment.

Power/Instrumentation/Controls. Because this facility was a warehouse space, adequate power distribution was not available to feed the new process, filling, and packaging lines. To address this problem, Matrix’s power engineer was responsible for upgrading the power distribution for the facility, a task that required design and specification of new MCC’s, 480V distribution panels, and 208V/120V utility power panels to supply process and facility loads. Matrix constructed a new 1,200 ft² electrical room to accommodate the new electrical equipment and upgraded the entire facility to LED lighting. Finally, working with the architectural group, the power engineer designed and specified a new 120V office lighting and receptacles plans for a 7,000 ft² office renovation.

Matrix’s instrumentation engineers worked closely with the process team to develop the instrument locations plans and specifications for the new process. This involved identifying and specifying over 200 devices and instruments, soliciting the vendor quotes, handling procurement services, and coordinating with the installation contractors. Matrix also developed the I/O schematic for the contractor installations and designed and procured the PLC control panels for the project that housed the new ControlLogix PAC.

Programming. Matrix Technologies provided the software development for the Process Supervisory Control System. Software design services included Functional Design Specification (FDS) Development, programming, pre-shipment testing, and automation equipment specification. Matrix’s automation team worked closely with the end-user’s automation, process, and operations teams from the initial development of the FDS through the pre-shipment testing. Following this project development methodology allowed for all parties to be aligned on the functional requirements and performance expectations throughout the course of the project, which also provided for a more efficient startup.

The Process Supervisory Control System itself was based on a ControlLogix and FactoryTalk View platform. Matrix’s automation team created a FactoryTalk View SE application to handle operations and developed the programmable automation controller (PAC) software based on custom-built phase logic, add-on instructions, and user-defined structures that were provided by the end-user. Our team also implemented several localized HMI stations throughout the process area for local control of the system and used a custom phase logic for control of several raw material tanks, a batch tank, transfer of product to a holding tank, filler supply, a reclaim tank, and a waste water tank.

Brownfield Site Success

Though the brownfield site presented some challenges, Matrix engineers were able to tackle the problems head on and provide the customer with a new facility that fits their needs. By using our expertise in the process of multi-discipline engineering, we were able to find solutions to challenges presented by abandoned and/or inadequate space, outdated electrical systems, and grading and drainage issues as well as plan and produce a manufacturing process that met performance expectations.

Matrix Technologies is one of the largest independent process design, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about process design capabilities and manufacturing process control solutions, contact Brett Rygalski, PE, LEED AP, Senior Project Manager.