At Predictive Engineering, we developed our expertise in computational fluid dynamics (CFD) consulting with years of CFD consultant project work in medical, aerospace, marine, HVAC, civil and automotive areas. Our work has been extensively benchmarked by experiments and in-service testing, giving us the necessary validation experience that allows us to provide world-class CFD service to our clients.
Our portfolio of case studies provides hard evidence of our many successful CFD consulting projects. These consulting endeavors include space-based communications equipment, hydroelectric spillways and HVAC air handling systems, to name just a few. In our CFD case studies section, you’ll find our expert work as consultants on a broad range of projects, including predicting the flow of diesel exhaust plumes, complex thermal problems with localized temperature extremes, conjugate convective-conductive thermal fluids analysis of a tightly integrated circuit board and fluid-structure-interface (FSI) work on hydraulic man-lifts or radar absorbing walls located in coastal airports.
We feel that our broad experience brings a fresh perspective to our clients’ CFD challenges. This experience provides a cross-pollination between industries that have shared physics but different structures. For example, a client had a flow-control value in a large water reservoir that under standard flow calculations would have required an expensive design change to handle the estimated forces. Our CFD consulting work showed that the hand-calculations were overly conservative and that the existing, budgeted design was adequate. Following our recommendations, the client went forward and the valve is operating per specifications. We know from our prior CFD service work on wind loaded structures, that given the same flow physics, the valve structure would behave similarly. In the interpretation of CFD results, experience is the key in knowing whether one has a cartoon or a real result that can be taken into production. We feel that this is our competitive edge and a proven value proposition that we offer to our clients.
If you have a need for experienced CFD consultants, Predictive Engineering has continually expanded its client base since 1995 with more than 800 projects to its credit. Our clients include many large organizations and industry leaders such as SpaceX, Nike, General Electric, Navistar, FLIR Systems, Sierra Nevada Corp, Georgia-Pacific, Intel and Bechtel.
Contact us to learn more about our CFD consulting services.
Some CFD Project Examples (text listing)
Thermal Modeling of High-Temperature Graphitization Furnace
In support of an ASME Section VIII, Division 2 thermal-stress analysis of a high-temperature furnace, several CFD investigative models were developed to bracket the thermal response of the system. A key question was how the graphite felt within the furnace would transfer heat to the inside steel shell of the furnace. Although the shell was water cooled, we needed to understand what might be the range of interface temperatures between the graphite felt and steel shell. A simplified 2D model was created where only radiative heat transfer was allowed across the interface and then only conduction. On the water cooled side of the shell, water was assumed to flow at a very reduced rate to mimic worst case conditions. This simplified model indicated that the graphite felt dominates the temperature response since the heat flux through the felt from 1650°C to the steel shell was minimal. Given the bracketed thermal response, the thermal-stress analysis was then executed with more reasonable confidence in the final numbers.
Improving the Thermal Performance of Bio-Fluid Containers
Of course, we all enjoy keeping our cold drinks cold and our hot drinks hot, but the thermal physics of designing such containers is quite complex. The margin in the numbers between hot coffee after six hours versus twelve is very slim given the temperature delta between the fluid and the outside, and of course, our preferred drinking temperature. Basically this means, the container must be very well engineered to maintain vacuum conditions between the linear and shell and that any conduction paths completely shut down. Our CFD engineering services concentrated on verifying our clients 1D thermal conduction-radiation-convection path and then creating a full 3D model of the container that could capture the internal buoyant convection of the fluid coupled to radiant heat transfer across the vacuum and finally to the external ambient air. The analysis was fully transient and provided insights into the dominate energy transfer paths through the container.
Flow Analysis of Novel Syringe for Ocular Medical Application
This CFD services work supported an advanced medical R&D effort to better understand how their syringe injection flow rates would vary given a range of plunger forces. The design was unique but attached to a common Luer system. The CFD modeling started out using an axisymmetric approach for efficiency but then as the project morphed, the model was setup as a full 3D idealization of the syringe and tissue system. Description and interpretation of the flow results were of pivotal importance to the group given that it provided them with on-demand CFD specialist without the cost and training of having a full-time engineer.
CFD Modeling of Flow Mixing in Large Wastewater Basin
This project somewhat completes our simulation of water treatment systems. In prior work for another client, we studied the flow of water through a flocculation basin and up through separators and then into the clear well. In this project, it was just the opposite since it considers the flow mixing of wastewater in a 110 ft diameter basin. Our client needed quantifiable proof that their mixing system would ensure complete mixing throughout the basin. Working collaboratively, the CFD model was constructed to represent the interior of the basin with known flow obstructions, skimmers and pumps. Flow results indicated that one 50HP mixer could provide complete mixing in the basin. Our CFD engineering report was then leveraged to demonstrate similar mixing confidence in other basins.
Thermal-Flow Analysis of Large Composite Curing Mandrel
Modern jet engines are getting bigger and also lighter; e.g., the prior titanium blade-out shield is now a carbon fiber composite. Manufacturing large diameter composites with tight tolerances requires high precision in the curing and cooling process. The CFD model simulated the cooling cycle of the system (composite and tooling) from its curing temperature down to room temperature. Results were verified against prior experience and hand calculations.
Mapping Envelopes of Expected Dynamic Behavior using CFD Flow Loading
Recently we just completed a coupled computational fluid dynamics (CFD) and finite element analysis (FEA) project on a “turbocharger” to an existing 60kW gas turbine. The energy physics of this turbocharger is to spray water droplets into the inlet of the compressor side of the turbine thereby increasing the density of the already 100% saturated air. This heavy air mixture is then combusted with increased gas flow, yielding a 10 to 15% boost in energy output from the turbine. In other words, one can take a 60kW turbine and turbocharge it to ~70kW at no more than 1% of the original turbine cost. The challenge for our client (an electrical utility) is that this device is bolted onto the flow housing inlet to the gas turbine. If this device fails, then parts would directly enter the turbine, leading to a very expensive repair operation plus unexpected disruption to the utility’s power grid. The graphics down below provide a generalized description of the CFD and FEA models. Air inters through the filter house and then around the housing, through some guide vanes and then into the compressor-side of the gas turbine. The CFD analysis (STAR-CCM+) provides us with component pressures over the housing and the water spray system which were then mapped onto a FEA model (FEMAP). The FEA model was then exercised through a static stress, normal modes and modal frequency analyses (NX Nastran). To verify this work, a CFD mesh convergence study was done and the FEA work was checked against hand calculations. Results assured the client that the add-on device was more than structurally adequate and could easily handle the power plant’s dominate 60Hz vibration plus any multiples.
Chemical Vapor Deposition (CVD) Reactor CFD Analysis
Temperature control in chemical vapor deposition (CVD) reactors is critical for creating high-quality product with minimal inclusions and defects. However, the thermal behavior of the reactor has a major impact of the structure itself, namely at flanges and other pressure-boundary seals. When a client wanted to redesign the main pressure vessel flange of a CVD reactor, transient CFD analysis was used to calculate the temperature profile of the reactor throughout the complete CVD processes. These temperature profiles were then used as inputs for an FEA analysis, allowing the client to optimize the new flange design using a robust set of loading conditions.
Flow Analysis of Novel Household HVAC Flow Vent
A local businessperson was on a quest to develop the next generation of household heating, ventilation and air conditioning (HVAC) floor vents. Prototypes were built and general flow intuition indicated that this new vent design should perform as well if not better than current designs. The challenge was how to quantify this intuition. Of course, an experiment could be performed but sometimes it is only necessary to quantify the difference and not be concerned with an exact measurement. We built side-by-side CFD models of the new vent and compared it with a standard floor vent. To no one’s surprise, the flow patterns were almost equivalent given standard house dimensions (i.e., ceiling height and room size). Armed with these results, the businessperson was able to move the project forward.
Rapid Depressurization Analysis of a Large Composite Container
A transient CFD analysis was performed to determine the maximum pressure difference that may occur during the rapid depressurization of the container via the triggered burst of the eight explosion vents at the ends of the container. The burst pressure of the vents was assumed to be at the upper limit of 1.25 psig. The container was assumed to be at nominal atmospheric conditions during a rapid cabin depressurization event creating a pressure delta of 8.3 psig between the inside of the container and the aircraft cabin pressure. Leveraging symmetry, it was possible to model the system using quarter-symmetry and then placed within an external air volume the simulated a typical aircraft interior, albeit in quarter-symmetry. Given the reduced model size, the transient CFD simulation ran in a couple of hours and generated the required transient depressurization curves to predict the maximum internal pressure that might occur within the container. To verify these results, the mesh was refined through several iterations. The calculated maximum internal container pressure was then used in the static stress analysis of the container by Predictive Engineering.
CFD Flow Modeling in a Cement Plant Bag House
This project was very much déjà vu since one of our first CFD consulting projects was a similar bag house model done in 1998. In this early model, we optimized the flow in 2D and then only made a few 3D runs since the analysis time was in days. Fast forward to 2015 and everything is in 3D and run times are in minutes given multi-threaded CFD solvers and faster hardware. The objective of this CFD service was to minimize the entrapment and accumulation of cement particles within the bag house. Along with minimizing the head loss the client wanted the manifold air flow balance to equally feed all twelve dust bags. The tuning mechanism was through the use of large vanes strategically placed within the manifold. After several iterations, the final design provided a consistent flow profile and avoided the settling of particulate at the bottom of the hopper.
Laminar Flow Modeling is a Large Water Treatment Basin
Drinking water every day from the tap, it is nice to know that the science and technology of water treatment is continuing evolving toward better processes. In this CFD project, we were tasked to investigate the flow of water within a large flocculation basin. Our client had years of experience in building treatment basins and wanted to improve their performance by ensuring that the flow behavior was as laminar as possible prior to passing through a series of flocculent traps (mechanical filters). The CFD model consisted of energy dissipaters (parabolic shaped plates with variable patterns of holes) and then large resistive blocks to simulate the mechanical filters. Interesting enough, our flow studies showed that their system was optimized and that further changes would be unnecessary given manufacturing versus performance constraints..
Electronic Cooling of High-Density Packages for Thermal Burn-In
Electronic devices used to be well-known to suffer from infant mortality. That is, they would work great for a few weeks or months and then just die during normal operation. The cause could typically be traced back to an overheated circuit or solder fatigue at the IC level; nowadays, advances in circuit testing and electronic device burn-in has largely solved this problem. Whereas circuit testing is a lot of signal processing, device burn-in is very thermal-mechanical with the controlled heating and cooling of the device and if needed thermal-cycling of the device to ensure its long-term survivability. Our client had the challenge of thermal-cycling thousands of electronic devices as rapidly as possible in a completely automated environment. They were recommended to Predictive given our past CFD consulting services for another company (it is small world). The CFD work consisted of local thermal-fluid models to determine optimum packing density of the devices for a given airflow to maintain tolerances of plus or minus two degrees centigrade. This local model was then simplified and used in a cabinet level model containing thousands of these devices. Airflow rates were determined for the given heating and cooling cycles along with ramp times. The overall model was then used to size the system’s thermal units and to convince the end-client that this novel design would work as intended.
HVAC Air-Handler Flow Blending Baffle Optimization
Roof top mounted air-handlers for large buildings are designed to balance foot print size and air handling capacity. To meet these specifications, the air blending chamber or mixing chamber between return air and outside air (make-up air) should be as small as possible yet still provide sufficient mixing that cold or hot channels don’t develop within the system. Traditionally, a large circular aluminum blade is used to direct the air into a similarly large chamber to limit head loss and provide sufficient mixing. This CFD flow study investigated a novel system of aerodynamic flow tubes combined with perforated plates to create a compact mixing chamber with similarly low, head-loss characteristics.
Analysis of Automated Test Stand for Solid-State Memory Devices
This CFD project was a combination of air flow optimization through constricted passages for minimal head loss and the development of internal baffles and air straighteners to create an even blanket of air flow over racks of solid-state memory devices. The thermal challenge was to ensure uniform air flow across the devices that would ensure as uniform heating and cooling rates and then maintain steady-state thermal conditions for burn-in testing. The analyses work was coordinated tightly with the client’s engineering team to ensure that the baffle design could be easily manufactured and that the thermal profiles would meet their specifications.
Natural Convection CFD Analysis on DC Power Inverter for Mass Production
A solar panel mounted DC power inverter was thermally analyzed using CFD to determine it maximum operating conditions in still air. Natural convection and radiation were enabled along with conjugate heat transfer between the printed circuit board (PCB), mounted integrated circuits, silicone based pottant and finally to its aluminum casing. Thermal CFD results were validated against experimental thermal images. The thermal work was then mapped onto a LS-DYNA model to simulate the expansion of the pottant against the chips and casings and to evaluate the overall water tightness of the casting on board level chip stress.
Bent Axis Hydraulic Pump Yoke - Pressure Drop Analysis
This analysis used a Computational Fluid Dynamics (CFD) model was to determine the pressure drop through a bent axis hydraulic pump under operating conditions. This analysis investigated multiple orientations of internal components affecting the flow path as well as multiple flow directions.
Pressure Drop Analysis of a Dump Truck Frame
Engine exhaust is routed through the ribs of the truck body to heat the body and help prevent dirt from sticking. The pressure drop of the exhaust through the frame cannot exceed the maximum allowable backpressure of the engine. This analysis simulated the flow through the truck frame. The CFD model of the frame was idealized as a solid air volume and with the adjacent steel structure.
Analysis of Parks RFTA Army Reserve Center
The objective of this analysis was to test the cooling and air circulation capabilities of a “green” building with ventilation driven primarily by natural convection. A large south facing atrium was used to create a chimney effect that would draw cool outside air in through the offices of the building. The results of this analysis provided the client temperature, air velocity, and flow path throughout the facility.
Relief Gate Flow Analysis
This CFD investigation was performed during the design process of a water control gate. The volumetric flow rate for the gate was given and the designers needed to be sure that the pressure drop across the gate did not exceed project allowables. In addition to the pressure drop requirements, it was important to determine the force on the gate from the fluid.
John Deere Manufacturing Building CFD Analysis
The objective of this analysis was to verify the HVAC design of a large manufacturing facility. The facility provided a complex thermal problem with many localized temperature extremes. Additionally, the facility experienced extreme winter and summer conditions that would test the limits of the HVAC design. The CFD model included circulation fans, HVAC ducting, gas heaters, lighting, air drafts from unsealed doors, heat loads from manufacturing equipment, and other temperature and flow inputs. The results of this analysis provided the client temperature, air velocity, and flow path throughout the facility.
Wind loading on Airport Noise Adsorption Wall
Wind loading conditions up to Beaufort Scale 7 were simulated on a large mobile wall structure using CFdesign. Wind load forces were directly mapped from CFdesign to Femap for structural analysis. Wind loads were checked against their upper limits using ASCE 7-02. The wall was designed to fit within a shipping container and is to be fabricated using standard steel tubing. The analysis work followed Universal Building Code (UBC) specifications for structures near human occupancy with a safety factor of 2x. Extreme wind loading conditions were also modeled and a nonlinear buckling analysis was performed to ensure that the wall would not collapse.
Thermal Fluid Analysis of Buried Pipe
This was a very interesting CFD analysis of buried plastic pipes under about eight feet of soil. The CFD work was coupled with a stress analysis models to facilitate a diagnosis of a pipe rupture problem. The CFD model was used to generate thermal profiles in buried piping vaults and in adjacent piping runs (SCH 80 PVC piping). Temperature profiles were then mapped onto the FE model to make predictions about piping stresses. The stress results correlated extremely well with observed in-field piping failures.
National Institute of Science and Technology (NIST) Investigation of Respirator Fit and Function
This was an in-depth detailed project to study the fit and function of a fireman type respirator mask. LS-DYNA was used to perform the fit study of the mask against a simulated human head. The silicone material model was easy to obtain while that for human tissue required some investigation. The best material model fit for human skin was that of a soft rubber compound within an elastic membrane. A transient flow study within the nose cup of the respirator mask was conducted using CFdesign. Inhalation and expiration studies were conducted using standard respiratory breathing curves. Transient flow results indicated that the standard respirator mask creates some turbulence during inhalation that might cause breathing difficulty. Research papers are in process to elaborate upon these results with a shared co-authorship.
HVAC CFD Modeling of Large Power Plant Buildings
Gas turbines for power generation, even with the best co-generation sub-systems, create significant heat loading within the power plant building. To complicate this matter, new noise standards for power plant buildings has required that these buildings be closed to the free flow of air from the outside. In essence, you have a heat generation source within a closed environment. To obtain tolerable internal operating temperatures through-out the year, a full computational fluid dynamics (CFD) study was done on two large power plant buildings. One building was a standard large hall configuration with the steam co-generation turbine at one end of the building the hall containing two large gas turbines. The other building used one massive gas turbine with a large HRSG (Heat Recovery Steam Generator) feeding to a steam generator. The building also contained two aux. boilers. In both buildings, cooling control was the biggest challenge since doors could not be opened during summer due to the noise limitation specification. As such, all cooling was by air conditioners. To limit the cost of air conditioning, only areas where human occupancy might occur were cooled letting other areas be hotter than normal but not to such an extent that safety was compromised. The CFD models were very large running in the range of 10 to 15,000,000 elements. Air flow was managed by placement of air conditioners and vents to the outside since makeup air was part of the equation. Winter conditions were also evaluated with building skin temperatures as low as 1.4 F. The buildings have been placed into service and are operating within the stated specifications as designed.
CFD Thermal Analysis of Speaker Enclosure
Compact stereo devices generate significant amounts of heat due to the high power generation of the amplifiers and face difficult cooling situations due to their tight enclosures, human safety concerns and that fan cooling due to noise generation is not permitted. CFD studies were thus focused on spreading the heat into surrounding structures or increasing the natural convection heat flow through larger heat sinks or better placement of these sinks. At times, the CFD work indicated that the design was simply unfeasible and a major rework of the speaker device was required. Most of these models were run as coupled thermal-fluid mode where air buoyancy (natural convection) was coupled to the solid chip components of the model. This is also known as conjugate heat transfer or conduction-convective heat transfer. In all, a desktop I-Pod stereo system, an amplified boom-box and several powered desktop speaker systems were successfully analyzed for thermal performance..
Scissor Lift Wind Load Analysis and Stability Analysis
A scissor lift with sensitive electronics equipment needed to be analyzed to determine the wind conditions it could withstand without tipping over. The CFD study allowed the client to give a wind rating with high confidence. It additionally saved the client thousands of dollars since they did not need to do physical wind tunnel testing. The tipping force was calculated at varying extension heights. The computational fluid dynamics (CFD) analysis was run to determine the force on the structure at varying wind speeds. These forces were verified against wind load calculations from ASCE 7-02, Minimum Design Loads for Building and Other Structures.
Parametric CFD Wind Force Analysis on a Residential Roof Mounted Photovoltaic Panel
The PV system consists of 4 modules that are aligned edge-to-edge to create an overall panel having dimensions of 130" x 62" x 2". The panel is mounted to the roof with 8 mounting brackets. The mounting brackets are 4" wide and are attached along the bottom and top edges of the PV Panel. Given this geometry, the panel was idealized as a 2-D structure. The PV Panel was mounted mid-way up on an inclined roof (10, 18 and 30 degree slopes were investigated). Mounting details and roof geometry are provided within the body of this report. The PV Panel height was investigated at 3.25, 4.5 and 6.0” heights. At the lowest level (3.25"), the rear opening underneath the aluminum rails and the concrete roof was blocked. At the 4.5 and 6.0" heights, the PV Panel was open on both ends. The wind load for this simulation was a constant 100 MPH air stream. Steady-state conditions were assumed.
Heat Sink Thermal and Pressure Drop Analysis
The objective of this CFD analysis project was twofold; determine the temperature of the heat sink during steady state operation and determine the pressure drop across the system. The temperature of the heat sink was critical as it had to be able to adequately cool the attached electronics. The pressure drop was important because the required flow rate and back pressure had to be taken into consideration when designing the air handling system. The system was analyzed under a range of air flow rates and inlet temperatures providing enough information to end client to interpolate for different operational scenarios.
High-Power LED Thermal Analysis
Phoseon is an innovative leader in the field of LED light bars that can generate intense UV light for a variety of industrial applications. These LED light bars present unique thermal challenges due to their high power and compact environments. The CFD model was constructed based on 3-D geometry provided by Phoseon. This geometry was slightly simplified for improved numerical performance. All flow was driven by a 40x40x28 Sunon fan that could deliver 24 CFM at 0.0 inch H20 backpressure. The fan curve was directly integrated into the CFD simulation. The flow through the light box was restricted by an exit baffle with 25% of its cross-sectional area blocked. This flow restriction increased the internal pressure within the box and drove a portion of the air stream through the exit passages drilled into the box alongside the high power LED arrays. Aluminum was used for all heat sinks. The heat generating chips were modeled as ceramic. A thermal interface compound was used between the high power LED arrays and its massive aluminum heat sink. Results were delivered on time and validated the design intent with only a few design iterations.
Analysis of Air Flow and Thermal Behavior of the Sandhawk Outdoor Electronics Enclosure
The CFD model was generated from CAD geometry provided by the client. An air enclosure was created around the system to allow convective heat transfer to the surroundings from the interior electtronics assembly (PCB and chips) thorugh the plastic enclosure. The back plane was assumed to be adiabatic and the front and side surfaces were set to the ambient far-field air temperature of 20 C. Power loads (Watts) were applied to the designated chips (marked with a stripe) and fan motor (2 W). The chips rests on a special conducting layer (1 W/m*C) which then is bonded to a large aluminum chunk. The chips are modeled as a glass compound with limited conductivity. The internal fan was driven by fan curve with a peak flow of 42 CFM.
Computational Fluid Dynamics Analysis of Automated Test Equipment
Predictive Engineering conducted a broad range of computational fluid dynamics (CFD) analyses for a major manufacturer of automatic test equipment (ATE). This ATE equipment addresses a broad spectrum of the semiconductor industry's testing needs for the design, validation, and test of analog, digital, memory, mixed-signal, and wireless semiconductor devices. The lion's share of the CFD work was executed to drive the design of a novel, high-chip density circuit board layout. Predictive results were then compared to experimental mockups and eventual drove the design away from forced convection cooling to one that more heavily leverages heat pipe cooling and other advanced circuit board cooling technologies
Analysis of Cable Assembly
Computational fluid dynamics (CFD) analysis was performed for a world leader in the design and manufacture of complete, turnkey cable assemblies for OEMs of ultrasound, surgical, and high speed data operations. Conjugate convective-conductive thermal fluids analysis was performed on a tightly integrated circuit board enclosed within a plastic case. Various cooling scenarios were investigated (forced cooling via a small embedded fan and natural convection) and chip junction temperatures predicted. Based on these CFD analyses, the circuit board chip density and power density (watt loading per chip) was optimized for long term thermal reliability.
Pressure Drop Analysis through Bag House
A 2-D and later 3-D CFD model was built of complex flow path through a large bag-house structure. The 2-D flow model was used for scoping work and then the final 3-D model captured the flow pattern from furnace gasses to fabric bag and final exit through scrubbing equipment. The predicted pressure drops due to passage way constrictions and filters were checked against prior experimental work and shown to be in good agreement. Based on the CFD results, the client proceeded with the construction of this multi-million dollar pollution control system.
Thermal Management of Large Cart-Based Ultrasound System
This project went on for years at a major international manufacturer of ultrasound systems. The thermal analysis was based on pushing air over an array of printed circuit boards while baffling the inlets and outlets to keep overall system noise low. Thermally, the project was not overly difficult since the electrical engineers had provided power dissipation levels for the chips and power supplies. The CFD model of the system assumed that the convective heat transfer from the chips and no thermal loss into the surround cabinet. Thermal results were validated against thermocouples and were found to be in tight agreement. Over the course of several years, dozens of models were constructed and validated. At our recommendation, the manufacturer brought this skill set in-house and we continued to collaborate with them to fine tune their CFD simulation process.