Meshing issue for CFA in Creo 7

Over the past few weeks our engineers have spent time with the latest version of Creo Flow Analysis in Creo 7 and we’re always keeping an eye out for issues our customers may run into. In this case we found a serious issue and want to share a workaround with the CFA community.

When creating CFA projects from Creo assemblies the meshing process regularly failed with a rather cryptic traceback. After some experimentation we found that this can be easily avoided by creating a CFA project with only the extracted volume part.

To do this generate your extracted fluid volume as normal with the assembly, then identify the name of that part. In file explorer navigate to your assembly folder and copy the same part into a new directory, this will be your CFA directory moving forward. Open the part by itself in Creo and create a new CFA project. The fluid volume has already been extracted so it can be directly specified as the fluid volume.

PTC has informed us that this bug will be corrected in a future release of Creo 7 but in the meantime I hope this will be helpful!

Hitachi Automotive Systems, LTD. discusses Particleworks

“Responding to the requirement to evaluate cooling performance, Particleworks had become one of the candidates for simulation. We had used FVM (Finite Volume Method) based grid method CFD software already, and we decided to choose the more effective one by comparing the time for pre-processing and calculation speed. Simulation of the piston oil jet shows that it is unsteady, the solid region moves, and the oil occupancy in the analysis region is small. Therefore, in FVM, oil was represented by VOF (Volume of Fluid) and solid movement was controlled by morphing the remeshing based on the movement profile written in text. On the other hand, in Particleworks, oil was represented by particles, and solid movement was controlled only by the movement profile. First, we compared the time for pre-processing. It took considerable amount of time to simplify the CAD model in FVM. It meant reducing the number of meshes and simplifying fine edges, and fillets required a lot of time and effort. Such a simplification process is often necessary with the grid method in order to avoid mesh breakage when using morphing. After that the process with meshing macro creation of moving boundaries, setting of analysis conditions, and trial calculation. At this time, the CAD model was not sufficiently simplified, and the mesh was broken during the trial calculation, which caused additional man-hours to simplify the CAD model again. In contrast, Particleworks does not use meshes, so there is no need to simplify the CAD model, which saves a lot of time. In Particleworks, a shape that maps the particle values is required when evaluating the average heat transfer coefficient of the cooling channel. So, we took time to make the patch area of this shape uniform in advance. Nevertheless, when comparing the total time for pre-processing, Particleworks resulted in less than 1/3 of FVM’s” Read the full interview here:

-Hitachi Automotive Systems, LTD.

FEV oil cooled eMotor for Electric Drive Unit

Particleworks is based on the mesh-free, “Moving Particle Simulation” (MPS) methodology. Particleworks can rapidly predict oil flow distribution, heat transfer and power losses, allowing engineers to study and maximize the cooling & lubrication efficiency. FEV used centrifugal oil cooling for significantly faster recovery after operating in the peak torque region. They were also able to achieve a 50% increase in power output and torque. Read the full case study here:

CFD testing of HeartAssist® LVAD performance under realistic working conditions

VADs are increasingly used to mitigate the shortfall in donor organs for cardiopathic patients awaiting heart transplants annually by providing a bridge-to-transplant, or to stabilize patients with congestive heart failure. While rotary VADs have smaller dimensions and simpler structures than pulsatile VADs, their continuous, high-speed, rotating blood-flow patterns represent a potential risk factor to patients from thrombus formation, thromboembolic complications or device malfunction due to pump thrombosis. Pump thrombosis is one of the main causes for device malfunction, and patients are exposed to the risk of sudden death or the risks involved in complex device replacement surgery. In this work, computational fluid dynamics (CFD) simulations were performed to mimic the realistic operative conditions of the VAD HeartAssist 5® (HA5, ReliantHeart Inc., USA). CFD analysis can be exploited to predict blood flow streamlines passing through these devices. Read the full case study here:

EnginSoft and the European Space Agency investigate hydroponic plant growth for future space missions

EnginSoft has been collaborating with the European Space Agency (ESA) for the past ten years, working actively in the MELiSSA program. At present, this project’s main efforts concern the life support system sector and the idea of creating an artificially closed ecosystem that generates food and oxygen for space crews on longterm missions. The current MELiSSA Pilot Plant (MPP), built to monitor the progress towards the goal, is located at the Universitat Autònoma de Barcelona. A 5-meter plant growth chamber, able to cultivate 100 plants and investigate their growth process, has been installed At the MPP, the Air and Canopy Subcompartment Analysis (ACSA) project was implemented to study the impact of airflow on hydroponically grown lettuce crops. Objectives The main objectives of this project were: – To improve the conditions in the growth chamber by reengineering the air management system; – To investigate the impact of airflow on plant growth. Computational Fluid Dynamics (CFD) Model of the system before the project The 5-meter plant growth chamber was replicated using a CFD model of the complete system. This model provided deep insight into the air distribution and the local environmental conditions around the aerial part of the plants

Ergonomic simulation – greater company competitiveness and improved productivity

A satisfied employee can work in a concentrated, motivated and productive manner. A well-designed workplace that meets ergonomic requirements allows for comfortable and painless work. By optimizing workplace performance, reserves can be activated and productivity can be increased in the long run. Read the full case study here:

Flow field optimization of a medical device

CAE is highly effective for product optimization. In this technical article, we describe how a hybrid method of computational fluid dynamics analysis was used to enhance the design of a medical device to improve its ability to maintain a stable microclimate around a patient, but also to reduce both the computational efforts and the time required to obtain these results. A microclimate requires the maintenance of specific values of temperature, humidity and air velocity around a patient.

One of the validated designs turned out to be very promising, as it obtains a further reduction of the heat loss compared to the best design of the NSGA-II first phase design optimization: a further 4% gained. As expected, this has been achieved by a solution that stays close to the limit value on the patient’s temperature and humidity, but still keeping a good margin from the assigned constraint value of 0.025. Read the full case study here:

Design and Analysis of Chain Drives made easy by RecurDyn Multi-Body Software

Chain models are among the largest and most complex that can be simulated with multi-body technology. First, depending on the chain length, the number of moving bodies could become remarkable. Second, contacts disturb the solution all over the chain, causing continuous impulsive excitation of the mechanism. Third, chain links are bodies with reduced inertia, whose motion is driven by stiff contacts and stiff bushings. RecurDyn has built its reputation on chain application. The main reason is its hybrid solver, which uses an innovative approach with respect to its competitor. Even chain models featuring hundreds bodies and thousands contact points can be simulated in a reasonable time. Read the full case study here:

Dana’s Use of a New Validated Approach for Advanced Design of Powertrain

Dana Incorporated is a valued automotive powertrain supplier because of the capabilities and value of their products. The Advanced Methods group at the Dana Technical Center looked for innovative technology that can be used in the engineering and design process for their products. In 2015, they evaluated the ability of Particleworks to predict the accumulation of oil on the surface of a rotating component within one of their axle assemblies. Particleworks is able to predict the oil accumulation on the spinning wheel on the right side of the axle assembly (top images are the side view, bottom images are the top view), with quite good matching the behavior in the actual physical test. Read the full success story here:

Intermarine Shipyard tests Flownex SE for its naval piping systems

There are various piping systems that convey many different fluids on board a vessel. Each fluid must reach its user at the right pressure and flow conditions. Accessories such as valves, bends, fittings and pipes induce pressure losses (as a result of factors such as pressure (p), flow rate (q) and pipe size (diameter, A)). The designer has to calculate these probable pressure losses in the pipeline in order to select (or verify) the size of the pump to be installed in the piping system to prevent a number of possible problems. Usually, these calculations to predict pressure losses are performed “manually” using the procedures described in the technical literature, such as the method of equivalent lengths, with the help of software such as Microsoft Excel or similar, and with the lengths and the fittings information being derived from one-line diagram (2D CAD software). The Shipyard wanted to test the capability of the 1-D computational fluid dynamics (CFD) software known as Flownex Simulation Environment (SE), provided by EnginSoft S.p.A., as a pipeline solver for its naval piping systems. Read the full case study here: