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Product Development
Integration of Flow Simulations
Obtaining reliable early findings about flow and heat transfer processes is often a crucial criterion for
the success of a development project. In some cases, concrete information about the physical flow and
heat transfer functions in a future design or method is required right from the definition phase. In the age
of Product Lifecycle Management (PLM) strategies, there is no longer any viable alternative to computer-based simulation.
Dr. Ivo Weinhold, Product Manager, NIKA GmbH
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Figure 1: Pressure loss in automatic filter
Picture: BOLL & KIRCH Filterbau
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Nevertheless, it is crucial that calculation projects can be completed on time and achieve reliable results.
Flow calculations that are not able to keep pace with the general progress of a project are less useful as
development tools. As a result, the efficiency of simulation calculations – not only flow simulations –
is determined to a large extent by the total processing time required. This begins with the provision of
3D CAD data for the design to be analysed and ends with the presentation of results and conclusions to the
decision-making bodies. Under practical conditions in development and design departments, this challenge can
only be met using specially tailored calculation tools. These tools must be designed in such a way as to free
the project engineer as far as possible from specific calculation activities and allow him to concentrate
exclusively on the actual resolution of the physical and technical issues. Crucial elements here include
handling of the CAD data for generation of the geometric model to achieve the maximum possible integration,
automatic grid technology, stability and reliability of the mathematical algorithms through intelligent
solution control and efficient evaluation and documentation of results.
CAD Integration or CAD Data Import
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The initial version of the geometry to be analysed normally exists as a 3D CAD data record. This data can be most
easily used for a simulation if the simulation program is integrated into the CAD system and can directly use the
system’s geometry functions. The Engineering Fluid Dynamics (EFD) software from NIKA for flow and heat transfer
simulation is integrated into CATIA V5 (EFD.V5) as a workbench and into Pro/ENGINEER Wildfire (EFD.Pro) as an
additional module and uses these systems’ respective user interfaces to access the same features as are available
for the geometry model itself. Changes and optimisations to the geometry based on findings from the simulation
calculations can be made directly in the CAD system using the familiar modelling functions. However, there are
also various areas where more universal handling of 3D geometry data is required. For example, many system suppliers
and engineering service providers process geometry data for simulations in a range of data formats and expect the
data to be seamlessly transferred using import interfaces for original data from all major 3D CAD systems and using
interfaces for universal standard formats such as STEP, IGES and VDAFS. It is important that the parameters of the
initial version of the imported components and assemblies are changed or supplemented for subsequent analyses and
can be returned to their original format for direct processing in the original system. To meet these requirements,
NIKA has developed the EFD.Lab program system, which combines the Engineering Fluid Dynamics technology for flow
calculations and a latest generation parametric volume modeller with a full range of interfaces. EFD.Lab thus provides
comprehensive CAD links for almost all important 3D CAD systems.
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Figure 2: Flow speed in a filter cartridge
Picture: BOLL & KIRCH Filterbau
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Automatic Grid Generation
The finite volume method has established itself as the fundamental calculation method for simulating flow,
heat and material transfer. This method requires a calculation grid in the area to be analysed. It is crucial
that this grid is of high quality in terms of flow calculations. The criteria include automatic generation of
hexahedron cells over the entire calculation area and a sufficient grid density in areas that are critical in
terms of the fluid mechanics, without allowing the calculation to become inefficient due to unnecessarily large
models. If the 3D CAD models created for the mechanical design and production are now used for grid generation,
a problem occurs: the area to be calculated – the space filled with liquid or gas – is not normally modelled as
a separate solid and is not therefore available for grid generation. To overcome this, the EFD programs can
automatically identify both the enclosed internal flow space and the outer flow area, as well as the solid areas
of different materials involved in heat transfer. A grid of hexahedron elements is then automatically generated
for the entire calculation area using RAM (Rectangular Adaptive Mesh) technology, and the grid density is automatically
adjusted at geometrically and physically critical areas.
Automated Evaluation of Results Using Standard Software
Efficient evaluation and documentation of the calculation results is another important factor in the total processing
time and thus in the total costs of a flow simulation. With MS Office, the PC platform provides a de facto standard for
creating documents or presentations and evaluating numerical material. The combination of MS Office with a flow simulation
program integrated into a CAD system or a volume modeller opens up new possibilities when it comes to providing effective
and practical access to the calculation results. For example, result data along a CAD curve can be extracted and
automatically presented and evaluated as a chart or table in MS Excel. Users can adapt the templates used to meet their
own individual Corporate Identity, allowing presentation-ready documents to be created.
Figure 3: Pressure loss in a simple filter
Picture: BOLL & KIRCH Filterbau
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BOLLFILTER Protection Systems
”In the past, the design of new filter developments was based on theoretical considerations and calculations,
for example pressure losses, and of course the experience built up as an established manufacturer”, explains Karsten Cartarius,
Development Engineer at Boll & Kirch Filterbau GmbH. “However, the design could not be verified until the initial prototypes
had been produced and by that time the design was normally well advanced and any changes were complicated and costly.
In addition, our customers often expect very precise design data at the development stage and then check this against the
final filters delivered. That was why we decided to introduce CFD.” The engineers chose the EFD.Lab simulation system from
NIKA because of its “focus on proper engineering methods and what we saw as its excellent value for money”. The initial
attempts at performing flow calculations were extremely positive, as Karsten Cartarius reports: “The introduction was easy
and the first simulation results were being incorporated into our designs much sooner than expected. EFG.Lab very quickly
became an indispensable tool that is recognised by all of our internal departments.” This success soon led to an expansion
of calculation activities: “Although we were initially interested primarily in calculating the pressure losses that are so
important to us as a filter manufacturer and in obtaining findings to optimise housing designs, we are now performing many
more analyses, including heating processes (heated filters), backwash and cleaning processes (filter cartridges in automatic
filters), flows of forces induced (centrifuges) etc. We also find the excellent options for creating documentation extremely
useful.” In summary, Karsten Cartarius concludes that: “Flow simulation is a vital requirement for us to realise our claim
of developing state of the art products. CFD is the only sustainable way to achieve this, and EFD.Lab has proved to be the
perfect choice for our needs.”
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» Special edition from CITplus, 6/2006 (PDF, 3.418KB)
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