11/8/2018 Heapy Engineering is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Competition for non-AIA member are available on request. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any materials, methods, and services will be addressed at the conclusion of this presentation. BRIEF OVERVIEW This presentation will provide an overview of computational fluid dynamics use in the built environment. CFD can provide a valuable design tool, allowing architectural and engineering flexibility to complex problems and building design. CFD can also provide noticeable cost savings, allowing evaluation of systems or concepts that previously were un-testable or required significant man-hours to complete. Included in the presentation are overviews of some of the various software packages that are available to the A/E for use in building and environmental design. The software applications shown will include those used for architectural assistance, mechanical design, fire protection design (smoke control), and data center thermal control applications. 1
11/8/2018 LEARNING OBJECTIVES • Attendees will learn how computational fluid dynamics can be utilized in the built environment to shape building system and design; • Attendees will understand the various applications that can be utilized during design; • Attendees will understand how CFD contributes to performance- based design; • Attendees will recognize how CFD can contribute to an overall design and construction cost savings. SPEAKER BIO Matt Sciarretti Daniel Lampke PE, CPD, CFPS, LEED AP BD+C PE, MS: FPE Principal, Tech Manager – Senior Fire Protection Engineer FP & Plumbing PRESENTATION OUTLINE 1. Background 2. Benefits of CFD 3. Applications A. Wind Modeling B. Smoke Control/Life Safety Analysis C. Thermal Comfort D. Data Center Modeling 4. Cost Savings Through CFD 2
11/8/2018 BACKGROUND – WHAT IS CFD? • Computational Fluid Dynamics • Combination of fluid mechanics, iterative numerical analysis, and computer science applications • Uses algorithms to calculate motion and effects of different fluids in a space with predefined conditions. • Allows early and accurate prediction of device/system performance. • Reduces need for analytical studies / prototyping. • Validates performance-based design. • Allows rapid iterative development/evaluation. WHAT CAN WE DO WITH CFD? We can now project the interaction/effects of fluid motion! • Fluids are everywhere – Air, water, fuels. • Can follow particles suspended in fluids too – smoke particles, chemical concentrations, etc. The following slides demonstrate capabilities of some software, including: 1. Smoke control/exhaust in an irregular atria; 2. Exterior wind modeling; 3. Thermal controls & adjustments in a multiuse room; 4. Data center airflow & thermal predictions. HOW CAN CFD ASSIST THE DESIGN PROCESS? • CFD Modeling can be used to predict real-world conditions and aid in design decisions. • Forecast various design changes. • Allows design professionals to provide a tailored solution or perform rapid iterative design. • Allows A/E to be more creative with design. • Approach can be validated thoroughly. • Visual representation of results. • Visuals can be very important during approvals/variance meetings. 3
11/8/2018 MANY MORE USES! Not an exhaustive list by any means – we cover 4 ways to use CFD modeling, but there are many other uses including: • Airflows around vehicle & equipment heat stress; • Design of plumbing fixtures / fluid mixing; • Modeling Engine ports – thermal effects & thrust; • Chemical dispersal models; • Clean room simulations; …and many others! Exterior Wind And Plume Injections Modeling WIND MODELING • CFD involves the modeling of particles. • What can also be represented as movement of particles? Wind! • Air/gases can be modeled in CFD programs, with velocity added to simulate air movemen t. • Uses for exterior wind modeling include: 1. Model the flow of air contaminants away from the building. 2. Analyze the effects of wind on an external sitting/eating area. 3. Investigate stresses on building elements during extreme conditions. 4
11/8/2018 WIND MODELING: EXHAUST AIRFLOW Evaluation of wind flow patterns against building geometry to determine if building equipment exhaust will be sucked in through fresh air intakes. WIND MODELING: CONTAMINANT DISPERSION WIND MODELING: OCCUPANT COMFORT • Wind can also be a factor for occupant comfort and space utilization. • Case Study - Wind Effects on Exterior Sitting Area. • Problem: Hospital’s rear courtyard cafeteria area reporting high speed turbulent winds. • Wind swirls were reportedly lifting mulch 3 stories to roof of building and toppling exterior metal trash cans. • Space was unusable for cafeteria. • Building was recreated in CFD and analyzed against the wind conditions of the various seasons. 5
11/8/2018 WIND MODELING: VERIFICATION OF EXISTING CONDITIONS • Courtyard wind vortex effect replicated in model. • Design was verified against known conditions to ensure model could provide a realistic analysis. • Once a baseline was established, then iterative design could progress. WIND MODELING: ITERATION & FINAL DESIGN Able to run 10 different scenarios. • 5 different protection schemes • 2 different material types Final Design – Sloping Solid Roof • Low wind speeds • No vertical wind movement Using CFD to analyze the previous building wind model resulted in an effective solution, developed with minimal man-hours and validated via software. If the solution was left to general contracting, there would have been greater waste in design iteration. WIND MODEL: The first initial design evaluations focused on SAVINGS owner’s suggested solutions, including a horizontal wind barrier (fence). CFD proved such a “solution” would have been ineffective. Use of software evaluation led to the correct solution quickly, and least overall cost. 6
11/8/2018 Smoke Control ATRIUMS • Any atrium connecting 3 or more stories requires a smoke control system. • The OBC & NFPA 92 outline calculation procedures for a simplistic, rectangular atrium. • Very prescriptive requirements. • Problem: most atriums are not rectangular. • Angled geometry, hanging design elements (artwork), irregular ceiling patterns: all affect performance of exhaust system. • Algebraic calculations, due to various assumptions, often result in excessive exhaust & make-up air. • How do we account for this and design an effective system? CFD Modeling. PERFORMANCE-BASED DESIGN IN ATRIUMS • CFD Modeling can account for all irregular geometries, exhaust system modifications, and different fire locations to fully evaluate the prescriptive design. • Can also be used for more performance-based smoke exhaust strategies. • Can calculate time-to-egress of occupants from the building, then demonstrate smoke layer descent versus occupied floor evacuation. • Compared to prescriptive design, CFD can potentially reduce equipment sizes while maintaining the same level of life safety. • Recognized by OBC and NFPA 92 as a viable and approved alternative to prescriptive design. • Validation tool – may satisfy fire prevention personnel without performing ineffective testing. 7
11/8/2018 SMOKE CONTROL – EXAMPLE EXISTING STRUCTURE WITH NEW 3 STORY ATRIUM 3D Perspective Plan View SMOKE CONTROL – RESULTS SMOKE CONTROL - RESULTS 8
11/8/2018 This atrium was very irregularly shaped, which did not fit general prescriptive code analysis. A multi-part finite element analysis would have taken an exorbitant amount of time and prone SMOKE to human error. CONTROL: CFD could be grouped with occupant egress SAVINGS calculations to validate life safety while the smoke was exhaust at the roof. Use of CFD reduced the prescriptive- calculated exhaust fan size by 35% (reducing generator size too!) ADDITIONAL EXAMPLE - SMOKE CONTROL SAVINGS • Another project involved the analysis of occupant egress capability within a lengthy, 4-story atrium. • System was functional and tested regularly. • However, due to atrium modifications, the exhaust system needed to be validated…and if not, upgraded! • Cost to upgrade ~ $4,000,000 – exhaust and makeup air fans, fire alarm system upgrades, generator replacement, etc. • Use of CFD with egress software validated the effectiveness of the currently installed smoke control system in maintaining life safety throughout entire building egress. Using CFD to predict the Thermal conditioning performance of passive conditioning systems 9
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