Access technical proceedings from past user conferences to learn about the many real-world applications of FLOW-3D products and the recent and upcoming developments for the FLOW-3D product suite.
New Conference Proceedings
The conference proceedings from the 2017 FLOW-3D Americas Users Conference are now available!
KEYNOTE ADDRESS: Multiphysics CFD: Challenges and Applications
Edward Furlani, University at Buffalo, SUNY
The interest in fluids and related transport phenomena has grown dramatically in recent years as applications have broadly proliferated. At the same time, advances in computational fluid dynamics (CFD) combined with ever increasing computational power at reduced cost have enabled unprecedented understanding of fluidic behavior and the rational design of novel commercial technologies. In this presentation, challenges and applications of multiphysics CFD are discussed. The applications range in scope from nanoscale photothermal bubble nucleation for cancer therapy, to magnetically-based microfluidic biosorting, to inkjet technology and liquid metal 3D printing, among others. The discussion will be reinforced with results from case studies.
FLOW-3D Solver Developments
Michael Barkhudarov, Flow Science
Flow Science is working on two major releases: FLOW-3D Cast v5.0 and FLOW-3D v11.3. The FLOW-3D Cast release sees an expansion of modeling tools to aid users in the design and evaluation of a casting process. Additions include the output of gas pressure and venting efficiency during filling, and thermal modulus and last places to freeze during solidification. A heat transfer coefficient calculator for conical sprays, based on the spray flow rate, has been added to the spray cooling model. The intensification pressure has been coupled to the air entrainment, void particles and porosity models. Users will now be able to use degrees Centigrade or Fahrenheit with negative values, overcoming a long-standing limitation in FLOW-3D. There will no longer be a requirement to define temperature in absolute units for models that use an equation-of-state, such as air entrainment and radiation heat transfer. A cluster version of the solver will also become available for FLOW-3D Cast this year. The two-fluid flow model in FLOW-3D v11.3 will see the introduction of a full two-temperature solver, enhancing accuracy and flexibility of the treatment of heat and mass exchange at the interface between the fluids. Users will also be able to apply transformations to whole geometry components, simplifying geometry setup for components made of multiple subcomponents. The shallow water model now allows the use of Manning’s coefficient to describe terrain roughness. The user will be able to choose whether to define pressure in gauge or absolute units in FLOW-3D v11.3, even when a model that requires the absolute scale, e.g., adiabatic bubble or compressible fluid, is used.
INVITED SPEAKER: Numerical Simulation of Air Entrainment and Transport in Low-Froude-Number Hydraulic Jumps
Fabián A. Bombardelli, UC Davis, Milagros N. Loguercio, National University of La Plata and Kaveh Zamani, Water Research Laboratory
We assess the prediction capability of FLOW-3D to reproduce the flow and air transport in hydraulic jumps for different low Froude numbers. We compare results including different levels of complexity in the theoretical model to predict the mean flow, turbulence statistics as well as, more importantly, void fractions. To the best of our knowledge, this is the first time a validation with an extensive level of rigor has been conducted. Due to the lack of experimental works including data for the mean flow, turbulence statistics and air concentration altogether, one flow was selected to first check the accurate representation of the mean flow in a low-Froude-number hydraulic jump, and then other laboratory tests were chosen to analyze the void fractions. Rigorous mesh convergence tests were done to validate the numerical models. Results revealed that the numerical model can reproduce the flow field and turbulence statistics in very good agreement with data, whereas the void fractions are not as accurate as the above but that they are still acceptable and of the same level of agreement with published works. The presentation addresses the behavior of the different complexity levels against data.
DISTINGUISHED SPEAKER: Going Against the Grain
Dr. Tony Hirt, Flow Science Founder and Developer Emeritus
Granular materials are ubiquitous. They are important in agriculture (seeds, grains, fertilizers), construction (sand, gravel, cement), pharmaceuticals (pills, powders) and, of course, the environment (debris flow, river and shore deposits, sand dunes, etc.). Most attempts to develop computational models for predicting the behavior of granular material have focused on discrete particle models. The drawback of these approaches is that in practical applications the number of particles is generally in the tens of millions to billions, limiting discrete particle simulations by computer memory and/or computational time. In this presentation, a more efficient continuum model is described that has been implemented in FLOW-3D. Computational results are used to illustrate the complex, and sometimes non-intuitive, behavior of granular materials that exhibit features of both fluids and solids. How does an hour glass work? Why can it be difficult to mix granular materials? Why does a shear flow reduce the settling of granular particles? These questions will be answered using simulations of simple flow situations. Combining simple physical models with guidance from basic experimental studies has resulted in a computational model that is able go up against the errant behavior of dense clouds of interacting grains.
User Interface Engineering
John Ditter, Flow Science
Our programmers and engineers continue to improve our user interfaces by working closely with our users to understand how they set up and analyze their simulations. The result is a more intuitive user experience and an improved workflow with fewer errors in simulation setup and faster post-processing. Today I’ll show how our latest interfaces improve user productivity. In FLOW-3D Cast v5.0, Process Workspaces have been expanded to include more casting processes. The process workspace approach is designed to simplify and improve users’ workflow. Another major feature – Customizable runtime plots – will allow users to continuously monitor the results of their simulations while they are running. Users can quickly decide whether to continue the simulation or if design changes are necessary. Other significant enhancements will also be introduced, including new databases and the ability to generate view files for batch postprocessing. FLOW-3D Cast v5.0 will also ship with an upgraded FlowSightTM with a new graphics engine and scenario viewer. Several new features and improvements to FlowSight, will also be described. Early next year, FLOW-3D v11.3 will incorporate many of the same enhancements included with FLOW-3D Cast v5.0, but will also include “smarter” shallow water mesh blocks, and an interface for the chemistry model.
Computational Analysis of Pinch-off Dynamics and Printability of Simple and Complex Fluids
Vivek Sharma and Jelena Dinic, University of Illinois at Chicago, IL
Drop formation and liquid transfer in jetting, printing, coating, and spraying as well as microfluidic drop/particle formation applications are accompanied by the formation of unstable columnar liquid necks that undergo surface tension driven thinning and pinch-off. Advances in high-speed imaging and visualization methods, coupled with advances in theory and simulation methods for free surface flows, have resulted in a fairly comprehensive characterization and understanding of capillary-thinning dynamics for simple, Newtonian fluids. For Newtonian fluids, the complex interplay of inertial, viscous and capillary stresses before and after breakup leads to neck thinning dynamics that can often be described by universal scaling laws, and selfsimilar neck evolution manifested in experiments. In rheologically-complex fluids, extra elastic stresses as well as non-Newtonian shear and extensional viscosity dramatically alter the nonlinear dynamics. Stream-wise velocity-gradients associated with extensional flows arise in thinning liquid necks spontaneously formed during printing, spraying and atomization, and fiber spinning. Complex fluids exhibit a much larger resistance to elongational flow than simple fluids with the same zero shear viscosity, leading to delayed pinch-off and dramatically changing the shape of the neck as well as rate of neck thinning, satellite drop formation and printability. Using the Volume-of-Fluid approach implemented in FLOW-3D, we simulate the free surface flows within columnar necks or stretched liquid bridges formed by dripping, by applying step strain to fluid between two parallel plates, and by dripping-onto substrate. Using these three prototypical cases, we simulate free-surface flows realized in printing as well as in extensional rheometry devices used for studying pinch-off dynamics and the influence of microstructure and viscoelasticity. In contrast with often-used 1D or 2D models, FLOW-3D allows a robust evaluation of the magnitude of the underlying stresses and extensional flow field (both uniformity and magnitude). We contrast our results with 1D and 2D models, and show that shape evolution dynamics, finite-time singularities, and satellite formation can be probed remarkably well with the CFD simulations in FLOW-3D. We find that the simulated radius evolution profiles match the scaling laws and pinch-off dynamics that are experimentally-observed and theoretically-predicted for Newtonian fluids. Finally, we describe our experiments and FLOW-3D simulations to elucidate how viscoelasticity modeled using the Oldroyd-B constitutive model influences interfacial and nonlinear flows underlying pinch-off dynamics, extensional rheometry and printability of polymeric complex fluids.
Two Fluid Modelling of a Spillway Flow
Stéphanie Thériault and Laurent Bilodeau, Hydro Quebec
We have been exploring the use of two-fluid modelling – air and water – for examining the flow downstream of a spillway gate. Our presentation will show how we went from one fluid to two fluids by means of a restart, plus a number of parameter and meshing adjustments. We will go over what worked well for us and how several pitfalls were circumvented.
Levelling System New Shipping Lock IJmuiden, the Netherlands
Randy Lagumbay, Arcadis-US, Jeroen Adema, Arcadis Netherlands, John Richardson, Arcadis USA
Arcadis is one of the consultants within the consortium OpenIJ that is building the new shipping lock in IJmuiden for the Dutch Ministry of Public Works. This lock, the biggest in the world, will improve the connection between the port of Amsterdam and the North Sea. The most crucial topic in terms of design was to show that the levelling system could meet the requirements on levelling times and forces on a moored ship. Three validation cases were carried out to show the reliability of FLOW-3D before we could start to model the levelling system. Grid sizes as small as 1 cm were required to model the geometry of the levelling system in enough detail to obtain reliable values for the discharge coefficient. Flow patterns were evaluated on the spreading of the high velocity zones downstream, which led to a design optimization of the breaking bar geometry. Energy losses and discharge coefficients were input to determine lift gate operations with the 1D model Lockfill. Physical scale model tests in the lab were used for the final check of the levelling times and forces on the ship. Discharge coefficients from FLOW-3D compared well with those of the scale model.
Making a Wave in Idaho
Bruce Savage and Greg Roberts, Idaho State University
Flooding events pose a risk to nuclear reactor facilities, as evidenced by the recent Fukushima Daiichi nuclear power plant failure and other flood events. To improve probabilistic risk modeling of these circumstances, water rise, spray, and wave impact testing capabilities are being developed for the Component Flooding Evaluation Laboratory (CFEL) at Idaho State University. The goal of the wave impact testing is to develop a device that can test prototype scale components for extreme wave impacts. The assumption is that a tsunami wave represents a worst-case scenario. The goal was to develop a device that can simulate the impact of tsunami wave heights up to 20 feet. FLOW-3D was used to evaluate and explore different conceptional designs including horizontal pistons, a vertical piston, or an air pressure system as methods of fluid displacement are explored. The results indicated that an air pressure system using baffles produced a near-vertical wave section.
Boundary Dam – Total Dissolved Gas Analysis
Nikou Jalayeri, Hatch
The Boundary Dam is located on the Pend Oreille River in northeastern Washington. The project consists of a 340 ft. high concrete arch dam, seven low level sluiceway outlets, two high level overflow spillways, and a 1003 MW powerhouse. The Boundary Hydroelectric Development have been shown to produce high total dissolved gas (TDG) concentrations in the river reach downstream. Studies were commissioned to determine modifications to the project’s spillway structures to help mitigate this gas production. Resolution of many of the hydraulic design issues for the study relied heavily on the results of numerical hydraulic models. These modifications were constructed and tested in the field. The CFD model that was developed in support of these studies was used to simulate flows through a number of the project’s seven sluice gates and two overflow spillways. The model was set up to track the pressure- and time-histories of representative air bubbles within the plunge pool and tailrace. These data were then used as input to a TDG predictive tool to help predict total dissolved gas production in the tailrace. The overall predictive performance was successfully calibrated and validated to actual prototype (field) TDG data.
Stratified Environmental Flows Interacting with Obstacles
Jian Zhou and Subhas K. Venayagamoorthy, Colorado State University
In this presentation, two published studies of stratified environmental flows interacting with solid obstacles using FLOW-3D will be discussed. These studies are respectively: (1) numerical simulations of intrusive gravity currents interacting with a bottom-mounted obstacle in a continuously stratified ambient; and (2) numerical simulations of the propagation dynamics of bottom-boundary gravity currents over and through a submerged array of cylindrical obstacles. In both of these studies, the numerical results from FLOW-3D were observed to be in excellent agreement with experimental data. With the aid of the robust numerical solver and the unique FAVORTM technique, the suitability and capacity of FLOW-3D to accurately model and provide fundamental insights into this important class of flows are demonstrated.
1Funded by the Office of Naval Research and the National Science Foundation
Advanced Research: Additive Manufacturing
John Wendelbo, Flow Science
Superior productivity and speed, coupled with low heat input are resulting in laser welding processes replacing more conventional welding methods. With better control and smaller heat affected zones, laser processing technology has enabled explosive growth in metal additive manufacturing processes such as powder bed fusion and direct metal deposition. This presentation shall provide a comprehensive overview of FLOW-3D’s modeling capabilities to simulate laser welding and additive manufacturing processes. Using case studies from industry and academia we will look at how process parameter optimization and relevant physical models play a key role in predicting porosity, surface finish and the subsequent microstructure evolution in welding and additive manufacturing processes.
Optofluidics: Modeling L2 lens
Adwaith Gupta and Ioannis Karampelas, Flow Science and Justin Kitting, University of New Mexico
This presentation describes the modeling of dynamically reconfigurable liquid-core liquid-cladding (L2) lens in a microfluidic channel using FLOW-3D, followed by quantitative validation against the experimental results. The lens is formed in a microchannel by three laminar streams of fluids with different refractive indices. The core stream, which is sandwiched between the cladding streams, has a higher refractive index, causing the light to bend while passing through the layers of microfluidic streams. Based on the relative flow magnitudes of the core flow rates and the cladding flow rates, different lens shapes (defined by the curvatures) are formed. Each curvature leads to a different focal length, thus governing the path of light rays passing through the microchannel. The case study is divided into two parts – constant cladding flow rates and constant core flow rates. Also, a technique is devised in FlowSight to find the curvatures of each lens. Finally, the results are validated against the experimental results.
State-of-the-Art Cloud Computing
Gandharv Kashinath, Flow Science and Will Cottay, Penguin Computing
Large models and detailed high-fidelity analyses are pushing the limits of in-house hardware resources. At the same time, engineering firms are running simulations as part of their design cycle more than ever and this is a growing trend. With advantages in hardware accessibility, cost, and ease of use, cloud-based solutions are gaining traction in the field of computer-aided engineering (CAE) and more specifically in computational fluid dynamics (CFD). FLOW-3D, in collaboration with Penguin Computing, is now offered in the cloud where thousands of CPU cores can be used to run either a few large simulations or many smaller ones simultaneously. This talk will focus on FLOW-3D ‘s cloud computing platform, its pricing, performance and ease-of-use.