Calculation service predict data The following data can now be accurately predicted using FabricAir’s CFD system (Computational Fluid Dynamic): • Terminal velocities • temperature gradients and • air distribution in any given space Simulations can be graphically presented in various ways making the task of interpreting the results easy from an engineering point of view. Data such as temperature gradients across the space, air direction and air intensity in different zones of the room is shown using the latest available graphics. The data is closely integrated with the confines of the space and takes into consideration such factors as supply air; return air and secondary entrained air streams. Hot air updrafts from human beings and other heat sources is clearly visible adding to the overall impression of the resulting air distribution picture.

Having CFD air movement simulation program available to Engineers, presents a quantum leap in air design.

We have for some time wanted to offer this as a service to our direct customers in conjunction with major projects where FabricAir distribution systems are planned says Tyge Hansen, Regional

Sales Manager of Chicago based FabricAir Inc. Our principals in Europe have used it successfully on various project and the calculation service is now available through FAI.

CFD 2D-graphic showing air velocity [fpm]. Showing one fabric duct in exhibition hall.

CFD graphic showing temperature gradient [°F]. Showing one fabric duct in exhibition hall.

	Smooth fashioned elbows in fabric add an aesthetic touch to the duct system.	Over 13,000 linear ft. of fabric duct is installed in this exhibition hall.	The fabric ducts are fitted with air directional and noiseless nozzles giving long penetrating air throws.	Prices for a run of simulation start at $ 3,500.00 and can be amortized in the final purchase of fabric ducts.

Air distribution in Exhibition Halls This type of facility requires careful planning of the air distribution system in order to achieve comfortable indoor air quality conditions in a space where the internal architecture changes from week to week. FabricAir’s CFD air simulation ensured correct terminal velocities and temperature gradient through a series of calculation with varying heat load concentrations. The final choice was fabric ducts with directional air throw nozzles ensuring thorough mixing of the conditioned and secondary air leading to an even air quality throughout the space. Supply detailed input Like most computer work requiring sound output data, CFD needs extremely accurate and detailed input facts to obtain a rational result. In addition to a precise room layout coupled with the fabric duct position, information such as air volume, temperature difference, internal and external heat loads, significant sources of heat producing equipment, and outside solar concentration is required. Given all of this information, an optimized image of the predicted air streams and comfort levels is processed. Air is no longer left to chance Engineers use a major portion of their time in plant and machinery design in order to match the cooling and heating loads; additional time is used in selection of control systems and other ancillary equipment. Having put together an optimum and coordinated package of air conditioning equipment, the actual air distribution system is in some cases left to chance, thus negating the attention paid to plant design.

The natur of cooled air: Cooled air being supplied at 45°F will, due to its density difference tend to drop down into a space and move towards the occupied zone by its own energy. Warm updrafts from humans generate a counter air stream. This well known fact is visually presented via a detailed CFD simulation.

CFD is the missing link between theory and practice CFD is the computation of fluid dynamics and involves the multiple simulation of the air currents and energy flow patterns within a certain model based on the space configuration and the expected temperature and air flow data. In order to make this as effective as possible, the space is divided up into a finite number of cells, each cell containing a control point. By means of transport equations and differential calculus the fluid dynamic interrelation between the control points and their respective boundary values are calculated, leading to a final graphic representation of the air pattern within the space.CFD is a powerful predictive tool and leads to qualified decisions being made when designing air distribution systems, this makes it particularly useful when considering air conditioned spaces requiring comfortable working conditions. CFD at an early stage CFD aids in a more conceptual understanding of the behavior of dynamic airflows. As such it forms a theoretical but sound basis for evaluating various solutions; with a view to selecting the final answers to any given airflow problem. This however does not necessarily mean that an absolute correct solution is found, and in this connection it is important to know the characteristics of the air terminal device so its particular performance criteria can be integrated within the CFD process.To get maximum benefit from a CFD calculation it should be carried out at an early stage in the project so various solutions can be considered in order to optimize the air distribution system and its effect.

CFD requires massive computing In order to accurately forecast an airflow pattern in the room, the computer splits up the space into millions of small cells, each one is simulated in relation to surrounding cells on a repeated basis requiring between 3.000 to 30.000 computations. Even at a processing speed of 14 GHZ, supported by 5 GB Ram divided over a cluster of 5 interconnected computers, a successful simulation can take between 4 to 48 hours of continual computer operation, depending on the system complexity. With the advent of high-speed E-mail services, a prospective user can access this computational service center with the minimum of delay.