CFD Computational Fluid Dynamics

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1 CFD Computational Fluid Dynamics Norconsult is both highly competent and has a broad experience in the 3D simulation of fluid flows. The section for Applied Fluid Dynamics utilises CFD in a multi-discipline approach, both across Norconsult's main market areas and in other, more specialised settings. The group is highly versed in leading, industry-standard CFD software. The group consists of engineers educated to both PhD and Master's levels, and between us we have a comprehensive background within CFD and applied fluids. Not only do we know how the CFD software can best be put into practical use, but we also understand the theoretical foundation, the methodology of the analysis, and the manner in which the results can be realised in real-world applications. One of our key competitive advantages is that we apply our knowledge in a multi-discipline fashion, both due to the nature of Norconsult as a company on the whole, and due to the mixed background of our fluids engineers. We therefore sit with expertise and practical experience in a range of fluid related fields, ranging from general external aerodynamics, to fire and explosions, and to urban flows and pollution dispersion, amongst others. Please see the links below for more information on the various market areas in which we are active: Aerodynamics Fire and explosions Rivers and coastal flows Marine applications Indoor climate and ventilation Urban flow and pollution Offshore and process industry Transport infrastructure Dams and hydropower

2 As the physics behind fluid flows and the methods used to simulate them remain unchanged across disciplines, the above links serve as examples of the type of services we offer. We welcome taking on projects outside these specific market areas, and encourage you to get in touch with us whatever the nature of your fluid-related enquiry. Please or call us and we can discuss your needs in more detail.

3 CFD Aerodynamics Aerodynamics, the study of the motion of air, is arguably the field for which CFD was first developed. CFD allows the complex effects of air passing over intricate geometries to be studied and analysed in-depth. When air passes over and past objects, its fluid properties, such as velocity, pressure, and temperature, can be significantly altered and many different flow-related phenomena may arise. Unexpected areas of high or low pressure, pockets of recirculating flow and buffeting, vortex dominated regions, or unwanted sonic effects are some typical phenomena that may arise. These can affect comfort levels or have undesired effects in terms of structural loading or air movement, for example. By using CFD to study a specific geometry, either as part of the initial design process or as part of a subsequent renovation, these potential phenomena can be identified. More importantly, their effects can be analysed, and recommendations as to their removal can be made and subsequently verified.

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5 CFD Fire and explosions Fires and explosions are phenomena typified by combustion, heat release, flame growth/dispersion, and pressure front propagation, amongst others. The successful prediction of the way in which these behave using CFD, be it in a town centre or a confined machinery room, can ultimately be lifesaving. Flows involving fires and explosions are driven by the release of thermal energy. A conventional fire releases its thermal energy through combustion of a reactant into flue gases or also termed smoke. The buoyant smoke gas can then be traced through a site (building) over time using CFD, which can aid in analysing the conditions during an evacuation scenario (available evacuation time). Measures for smoke control, for example; HVAC-systems and smoke layer curtains, can be included in the model to analyse their effect on the evacuation conditions. In addition one can study the effect of thermal radiation from the fire further effecting evacuation, but also the integrity of materials in the surroundings. Whereas a conventional fire releases its thermal energy at a relatively slow rate, an explosion, be it a bomb or a deflagrating accidental release of gas, releases its energy at a much higher rate. The rapid energy release causes the surrounding gas to expand, resulting in a potentially dangerous pressure wave. When an accidental scenario has been set, the pressure wave can be traced through the domain and the overpressure s damaging effect quantified by the use of CFD. For open landscapes there exist scaling laws for the pressure wave that can be calculated through pen and paper, but when geometry confines the area (e.g. through a street canyon or inside a tunnel) the problem gets more complicated and more suited for CFD-analysis.

6 Smoke layer approaching from other side of atrium

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8 CFD Rivers and coastal flows River, open channel, and coastal flows are usually characterized by a free water surface and complicated flow fields caused by combinations of complex bed topographies, irregular curvatures, and manmade structures. The flow of water in such areas or passages is either driven by gravitational or by tidal forces. The challenges of modelling these kinds of flows can be handled well by 3D numerical code. Through the use of CFD analysis, variables such as water levels, velocity distributions, pressures and substances transported within the flow can be quantified. Any free surface shape including hydraulic jumps, shockwaves due to supercritical flows, and the unsteady water level behaviour caused by flood or tidal waves can be predicted. The ability to predict the forces on the bed and banks caused by sea waves or water flows is essential in limiting damages in those areas or designing geometry to achieve certain goals. A wide range of applications is covered by us using CFD: Hydraulic loss calculations Propagation of chemical substances Identification of flooding areas Prediction of water levels Subcritical and supercritical flows Hydraulic jumps Sediment movement and scour potential Tidal affected flows Wave breaking structures Density driven mixture processes

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10 CFD Marine applications Engineering applications in the Marine setting can include a wide range of issues, including those related to marine structures, such as ship hull design, propeller cavitation, and ballast tanks, or those related to biological or environmental factors such as oil spill analysis, ship exhaust dispersion, fish oxidation and transport systems, for example. The marine sector includes both external flows (hull design, lifts through the splash zone) and internal flows (tank sloshing, bio tanks for fish transport) osv. All of which are suitable for studying through a CFDtool. Our experience and our knowledge of CFD allows us to analyse and consult on issues such as: Ship design and drag Tank sloshing Bio tanks (flow pattern, residence time and oxygen levels) Analysis of lifts through splash zone Waves Mer

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13 CFD Indoor climate and ventilation Appropriate levels of temperature, humidity, and air velocities in indoor settings are vital in ensuring adequate climactic conditions, whether they are specified by health and safety regulations or simply by personal comfort. CFD allows the air flow in an environment, be it an office, a building atrium, a concert hall, or a largescale shopping centre, to be analysed and subsequently optimized. Such areas are typically ventilated by mechanical means, and these ventilation systems can be modelled to ensure that they provide the necessary distribution of fresh air to ensure a comfortable climate. The placement of air inlets and outlets is important to ensure an even dispersion of air. If the locations of inlets and outlets are not optimized from the air-flow point of view, but, for example, are dictated solely by structural considerations, the ventilation may be inadequate. Areas of stale air or regions with inappropriate velocity (such as drafts) or temperature levels may develop. CFD can help visualise the movement of the ventilated air, and can analyse local air change rates.

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15 CFD Urban flow and pollution The analysis of wind in built-up areas and of pollution dispersion has been in increasing demand over recent years, and CFD is becoming the favoured tool in the field. The design and lay-out of built-up centres, and the way in which the buildings interact with the local wind conditions, can significantly affect comfort criteria at street level and the way in which pollutants spread throughout the area. The shape of buildings and the organization of streets and alleyways can create undesired and unforeseen aerodynamic effects. Certain building shapes can cause pressure build-ups or interact with the street layout, for example, to create pockets of high speed airflow or regions of separation and buffeting. This interaction can be exacerbated by specific wind conditions, such that significant problems arise, be it wind or noise discomfort for pedestrians, or high pressure/loads on building structures or doors. The ways in which new buildings aerodynamically interact with their surroundings are not necessarily clear or easy to understand when the building is considered or designed as a stand-alone entity. A CFD analysis can highlight potential problems and specific weaknesses with a building's design or placement. Moreover, the aerodynamic effects which may arise when considering the street and building layouts can also affect the spreading of pollutants and the air quality in the area. This is especially important in congested city-areas with busy roads where pollutant levels, such as NO2 and PM10, may collect and exceed acceptable limits.

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19 CFD Offshore and process industry Offshore and process industry installations may feature complex geometries, may be exposed to harsh atmospheric conditions, and may deal with a wide array of flow related phenomenon, all while having to meet strict technical regulations. When dealing with potentially dangerous substances, toxic or flammable gasses, and extremes of pressures and temperatures, it is important to be able to predict, for example, the effects of volatile wind conditions, the consequences of unexpected gas release, or the efficiency of ventilation systems, not to mention the potential for chemical or exhaust contamination of the surrounding environment. Health and safety is of utmost importance in both the oil and gas and more general process-related industries, and over the years extensive sets of technical requirements have been developed. Requirements deal with a variety of issues, including indoor and outdoor working environments. Aspects such as operating air temperatures, chemical exposure, exhaust contamination, ventilation capabilities (both mechanical and natural ventilation), and wind chill are carefully regulated. Our experience and our knowledge of CFD allows us to analyse and consult on issues such as: Placement of external inlets and outlets of ventilation systems Prevention of ventilation system short-circuiting and exhaust contamination Natural ventilation of open and semi-enclosed areas Wind chill and unavailability of open and semi-enclosed areas Gas release Mechanical ventilation of enclosed areas Analysis of pressure vessels Spreading of chemical/exhaust concentrations in working environments Our work is done in accordance with ISO 15138:2007.

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23 CFD Transport infrastructure Norconsult has an established track-record in the field of transport infrastructure including train and car applications, and projects typically involve infrastructure such as underground tunnels or underground stations. Typical issues with underground installations and tunnels tend to be pressure phenomena and ventilation. A high speed train entering into a tunnel creates a significant pressure build up as it enters the tunnel portal, and this can create a complicated pressure wave system as the pressure propagates and reflects down the length of the tunnel. If left unchecked, such a wave system can create sonic booms and can cause significant discomfort for passengers waiting at underground stations connected to such a tunnel.

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26 CFD Dams and hydropower The optimization of flow conditions upstream of, through, and downstream of dam structures is essential in ensuring peak efficiency, maximizing power output, and reducing environmental effects of hydroelectric installations. CFD can visualize complex 3D water-flow-fields that cannot be investigated by empirical 1D and 2D approaches which are based on assumptions, not generally valid. Those investigations can be done for steady state or transient, pressured as well as free surface flow situations and are able to handle geometric structures of any kind. CFD is generally used for estimating the discharge capacities, water levels, velocities, pressures, flow patterns and distributions of any physical quantity transported within the flow. CFD helps to optimize the design of hydraulic structures and to test different operational scenarios resulting in reduced vortexes, minimized losses and therefor higher efficiency, reduced costs and construction time. A wide range of applications is covered by us using CFD: Hydraulic structures (intakes, sand traps, weirs, amongst others) Design of new or redesign of old hydro power plants Flow situation within reservoirs up and downstream of hydraulic structures Spillways and hydraulic jumps Flow over side weirs Fish migration facilities Flow confluence in tunnels and rivers Hydraulic loss calculation Sediment movement and scour potential Tidal affected flows

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