We understand that CFD modeling can be challenging, especially for cases with complex geometries and multi-physics phenomena. That’s where our consulting services come in. At Convergent Science, we offer expert guidance to help you approach your toughest fluid flow problems with confidence. With CONVERGE’s wide array of state-of-the-art tools, we can help you make informed decisions to drive your simulation forward, while saving you time and resources in the process.
How it Works
Are you stuck on a CFD simulation? Can’t get your chemical mechanism reduced the right way? Or maybe you’re unsure if your problem can even be solved using CFD. Reach out to us, and our team of CFD experts will be happy to help you find the right solution for your engineering needs.
Our Consulting Capabilities
Chemistry Calculations
CONVERGE includes the SAGE detailed chemical kinetics solver, a robust tool for modeling detailed chemistry in a variety of systems. SAGE is fully coupled with the flow solver and can achieve accurate and efficient results. To obtain targeted insights without modeling a complete physical system, users can employ CONVERGE’s chemistry-related utilities to study specific aspects of chemistry. These tools allow combustion CFD engineers to study reacting systems, select and manipulate reaction mechanisms, and generate tables as needed for certain combustion models.
Detailed chemistry mechanisms often incorporate hundreds or thousands of chemical species and reactions. CONVERGE allows you to generate a computationally efficient skeletal mechanism by reducing the number of chemical species and reactions while maintaining solution accuracy.
We have worked with our clients to reduce chemical mechanisms to suit their specific needs. We used the surrogate blender tool to create a fuel surrogate that matches the target fuel properties provided by the client. Based on the fuel surrogate, we then used the extraction tool in CONVERGE Studio to extract fuel chemistry from the parent C3 mechanism, a large repository of chemical mechanisms that serves as an all-inclusive solution for combustion chemistry.
In another consulting project, we helped our client evaluate the potential risk of a burner flame backfiring into a room containing fuel vapor. In addition to accurately generating a skeletal mechanism to represent their test fuel, Convergent Science engineers used CONVERGE to model the evaporation, convection, and combustion processes, allowing them to determine fuel concentrations and flow rates in the burner. Conjugate heat transfer (CHT) modeling was used with detailed chemistry to model a flame arrestor, which prevented the flame from escaping into the room.
Combustion Systems
Opposed-piston engines have two pistons that move in opposite directions within the same cylinder. The opposed-piston design eliminates the need for multiple cylinder heads, improving efficiency. These engines are typically used in large industrial applications, such as power generation or marine propulsion.
In a consulting project for an opposed-piston engine, our engineers worked with the client to develop and validate an open and closed cycle in-cylinder model. In subsequent phases of the project, CONVERGE was used to develop two predictive metal temperature modeling approaches, one for the engine block and one for the pistons. CONVERGE’s volume of fluid (VOF) modeling accurately captured the oil sloshing in the crankcase and the oil gallery of the piston. CONVERGE’s void fraction-based Adaptive Mesh Refinement (AMR) and region definition helped track the mass transfer between different zones of the gallery. In addition, the Particulate Mimic (PM) soot model was used with the SAGE detailed chemistry solver to predict emissions parameters such as soot mass, volume fraction, soot diameter, and surface area.
CONVERGE has also been used to analyze cold start conditions in an opposed-piston diesel engine architecture. In a consulting case, CONVERGE’s zero-dimensional chemistry tools helped determine the temperature of the fuel mixture for optimal ignition, and the surrogate blender tool helped identify a fuel surrogate for the initial simulations. Our engineers first ran a closed-cycle simulation, which had the advantage of quick project turnaround and was used to determine the baseline setup. However, in every engine cycle, some fuel is deposited on the piston walls without fully evaporating (i.e., residuals), which can affect the ignition of the next cycle. To more accurately represent these residuals, we ran subsequent open-cycle simulations, which reflected the engine’s real-world dynamics. These open-cycle simulations successfully captured ignition criteria under cold-start conditions. In the final phase, we investigated the effect of fuels with different cetane numbers on ignition to find the optimal fuel blend for various cold-start scenarios.
In another case, our engineers studied flashback behavior in a premixed hydrogen-methane burner. Using the axisymmetric solver, they ran multiple simulations and developed a baseline setup and mesh strategy that accurately predicted flashback behavior with a minimal margin of error. Species-based AMR reduced the computational cost of modeling the early flame development while maintaining the accuracy of the overall simulation.
CONVERGE has a strong reputation for engine simulations, but our solver is certainly not limited to the automotive industry. For example, we have also consulted on a burner for the food and beverage industry. We extracted the appropriate chemical mechanisms from C3Mech and used them along with the SAGE detailed chemistry solver for combustion modeling. The RNG k-ε model accounted for turbulence, while AMR and fixed embedding ensured sufficient mesh resolution. To accurately simulate the burner, a part of the geometry was modeled as a porous medium with prescribed coefficients, and we modeled heat transfer inside the porous media.
Fluid Flow Control Systems
Valves, pumps, and compressors are devices that ensure the proper regulation of fluids and pressure within various systems, enabling reliable operation across industries like manufacturing, aerospace, healthcare, and more.
While working with a client on an internal combustion engine, we simulated valve movement and deflection during the engine brake cycle using an FEA—CFD coupled approach. CONVERGE seamlessly interfaces with the Abaqus FEA solver to facilitate runtime data exchange. This coupling enables advanced fluid-structure interaction (FSI) simulations involving complex solid deformation.
We have also simulated a single-cylinder reciprocating compressor and found the optimal setup for cylinder pressure. We ran multiple simulations to analyze the result sensitivity to grid resolution, outlet pressure, reed valve stiffness, and inlet temperature.
CONVERGE was able to properly diagnose and fix a discharge valve that was failing due to erosion and cavitation. With our innovative models, we were able to understand the fuel flow in the pumping cycle, which was causing cavitation and fatigue damage. Our assessment analyzed the ball check valve velocity, fluid velocity, vapor pressure near the valve, and the vapor fraction in the fluid.
On Land and Sea: Harnessing Wind Energy
Wind energy is a major pillar in combating climate change, with technological advancements enabling more efficient power generation for various applications. CONVERGE contains a range of innovative tools to help engineers optimize wind turbine design by accurately simulating aerodynamic forces, environmental factors, and turbine performance.
In a CFD study of an offshore wind turbine monopile, CONVERGE was used to study the pressure forces on the monopile and optimize venting pipe design to withstand wave effects. We calculated the water pressure from the fifth-order Stokes wave theory, which accounts for both hydrodynamic and hydrostatic aspects. We used the Smagorinsky LES model to predict air chamber pressure, vent pipe blockage by water backflow, flow rate, and chamber actuation.
We were also asked to assess the difference in performance and stability between two floating offshore wind turbines of different hub heights. The incompressible multi-phase solver was used with CONVERGE’s VOF modeling, an Eulerian approach that accurately captures complex interface dynamics between immiscible fluids. CONVERGE’s autonomous meshing automatically created a high-quality Cartesian grid, which was refined and coarsened throughout the simulation with AMR. The rotor blades were modeled using the actuator-line model (ALM), which represents each 3D blade as a 1D line. This method speeds up turbine simulations, while effectively capturing essential 3D flow structures.
User-Defined Functions and Post-Scripts
User-defined functions (UDFs) allow the user to extend the functionality of CONVERGE and generate custom code to suit their specific problem. For example, CONVERGE users have written UDFs to model wind turbine aeroelasticity, simulate the spark ignition (SI) process in SI engines, and analyze the effect of human respiratory events on viral transmission. UDFs allow users to control initial/boundary conditions, material properties, dynamic simulation parameters (e.g., time-steps, events), complex models (e.g., turbulence, combustion, parcels), and more.
In cases with cavitation, there are two common ways to predict the destructiveness of the vapor bubbles as they collapse. Our engineers used CONVERGE to create a UDF that would compute both the vapor volume change and the acoustic pressure wave acting on the wall, and presented them in a clear, comparable format to predict cavitation damage on an automotive fuel injector.
While UDFs are custom-generated code used to modify or supplement CONVERGE’s capabilities, post-scripts are written after the simulation is run to analyze or visualize CFD results. We developed an independent post-script for diesel and gas engine modeling in CONVERGE that would systematically check whether or not a given simulation setup correctly followed a predetermined set of guidelines. The script analyzed information about CONVERGE input files, related model variables, and specified values to return outputs in a ternary layout—pass, fail, and warn.
What’s Next
Do you have a CFD problem that you’d like some help with? Contact us to learn how you can use CONVERGE’s consulting services to advance your simulations today!
