CONVERGE CFD Software

Applications

Oil & Gas

The oil and gas industry is deeply woven into the fabric of our everyday lives, powering everything from transportation to electricity. It fuels the cars we drive, the planes we fly, and the industries that produce the goods we use. CFD offers valuable insight into oil and gas applications to drive this industry forward, providing detailed simulations of fluid flow, heat transfer, and environmental interactions. CONVERGE, a robust CFD solver with a unique autonomous meshing approach and wide portfolio of advanced physical models, is capable of effectively and efficiently modeling a wide range of oil and gas applications.

Multi-Phase Applications

Sloshing Tanks

Sloshing refers to the movement of liquids within a closed volume, which occurs when external forces act on the liquid, causing acceleration, deceleration, waves, or other oscillations. Sloshing liquids can have significant effects on the stability and structural integrity of the tanks that carry them. Studying sloshing dynamics with CFD can enable the design of safer and more efficient tanks to ensure they can withstand the forces they encounter during transportation while minimizing the risk of leakage or damage.

In CONVERGE, you can simulate sloshing tanks with the volume of fluid (VOF) method, an Eulerian approach where all phases are treated as a continuum. In this method, the cells of your simulation are assumed to be perfectly mixed, with a single value for parameters such as temperature, pressure, and velocity. In addition, CONVERGE’s Adaptive Mesh Refinement (AMR) technology helps to reduce numerical diffusion at the interface by refining the mesh at each time-step to add cells where and when they are needed to capture the relevant physical data.

Slug Flow

Slug flow is a multi-phase flow pattern characterized by the intermittent sequence of liquid slugs and gas pockets flowing through a pipe. While liquids tend to settle at the bottom of pipelines, gasses occupy the top section; under large pressure or velocity differences, the two phases may group together to form a slug. Slug flow can lead to significant pressure oscillations and mechanical stresses, raising concerns for safety and efficient transport of fluids in the oil and gas industry. By analyzing slug flow behavior, CFD allows engineers to study the formation, size, and movement of slugs to optimize pipeline designs. 

CONVERGE’s Multi-Fluid Multi-Field (MFMF) model is an alternative method for modeling multi-phase flow. The MFMF model calculates the continuity, momentum, and energy equations for every species individually; this feature enables the simulation of multiple interspersed immiscible species, in the form of liquid drops, gas bubbles, and solid particles. To capture slug flow, CONVERGE users may employ either the VOF or MFMF models with surface compression front capturing and active gravity and lift forces. 

CONVERGE simulation of slug flow, colored by the mass fraction of oil, water, and air (from top to bottom).

Three-Phase Separator

Three-phase separators are extremely useful in the oil & gas industry, particularly in petroleum production and management facilities. These devices rely on gravity, centrifugal forces, or filtration to separate oil, water, and gas from an inflow fluid. This separation ensures extracted water is free from contaminants before it is further processed or transported, facilitating continuous production. To optimize separator design and operation, CFD can simulate the fluid flow, analyze separation efficiency, and identify potential areas for improvement. Therefore, CFD engineers can assess how different designs might perform under varying conditions, creating more efficient separation processes and reducing the risk of operational failures. 

To investigate the efficiency of oil, gas, and water separation from the inlet flow, the difference in separation rate for each species can be captured by CONVERGE’s VOF or MFMF modeling. CONVERGE’s autonomous meshing, which generates a collocated cut-cell Cartesian mesh at runtime, eliminates user meshing time, while AMR and the surface compression scheme can capture a sharp interface. For multi-phase flows where the different species/phases move at different velocities due to inertial or gravitational effects, users may employ the drift flux model, which solves for mixture-averaged velocity by modifying certain source terms in the transport equations.

Offshore Energy

Capping Stacks

A subsea capping stack is not in the water during drilling; rather, it is the centerpiece of a containment system kept at a nearby onshore location. Since it is only deployed after the subsea blowout preventer has failed, it serves as the second line of defense in preventing oil spills. A capping stack’s primary purpose is to temporarily stop or redirect the flow of hydrocarbons, buying time for engineers to permanently seal the wellhead. This giant piece of equipment can weigh up to 100 tons, which makes maneuvering the device to seal the small opening of the blowout preventer quite difficult. CFD can model capping stacks to inform well control decisions and response operations, prevent incidents, and minimize risk.

CONVERGE’s fluid-structure interaction (FSI) modeling with six degrees of freedom (6DOF) can calculate the forces exerted by the fluid on the solid, predict how the structure will react, and move the solid accordingly. Additionally, autonomous meshing and AMR make the software well suited for simulating the complex geometry of the stack, the associated flow features, and the fluid’s interaction with the stack. VOF modeling can capture other facets of this case, such as the dispersion of the oil jet into the surrounding water

Video simulation of subsea capping stack placement using CONVERGE.

Floating Offshore Wind Turbines

Offshore winds are typically stronger and steadier than onshore winds, making them a source of largely untapped potential for wind energy production. Recent technological advancements have turned the vision of harnessing offshore winds into a tangible reality, paving the way for the future of sustainable energy. Designing floating offshore wind turbines (FOWTs) is complicated due to the dynamic coupling between wind and wave loads, intricate cable movement, flexible blade responses, and more.

CONVERGE includes several tools that are indispensable in FOWT simulation. With rotor models such as the actuator-line model (ALM) and the rotational actuator-disk model (RADM), you can efficiently capture the aerodynamics of the turbine rotor. A cut-cell Cartesian mesh captures the platform geometry, while 6DOF FSI modeling can simulate the interaction between the wind, waves, and turbine platform. Additionally, free surface models including the void fraction solution and individual species solution can simulate multi-phase flow, with front capture methods for the air-water interface. What sets CONVERGE apart from other CFD codes is its ability to simulate the various phenomena of FOWTs in a single simulation, creating a one-stop shop for modeling floating offshore wind turbines.

CONVERGE simulation of a FOWT

Pumps

Piston Pump

A piston pump is a type of reciprocating pump, where the reciprocating motion of a piston forms a chamber. When the pump expands, the chamber draws in fluid through a valve; when the pump contracts, the chamber expels fluid through a separate valve. While these pumps are commonly used in the oil and gas industry for their overall simplicity, challenges may arise due to valve movement, vibrations, or cavitation effects.

In CONVERGE, autonomous meshing significantly simplifies the mesh generation process, while AMR refines the mesh at each time-step to resolve areas of high velocity. A two-way coupled FSI approach, used with the spring and stiction force models, can account for piston motion. When these features are combined, setting up and running multi-physics simulations with moving geometries can be as straightforward as working with stationary ones.

Tubing Pumps

Another type of reciprocating pump, tubing pumps are often used in the oil and gas industry to lift fluids, such as oil or water, from deep within a well. In operation, they create a pressure differential which drives fluids upward. Since these pumps are meant to be used for subsurface operations, they must be designed to function under high pressures and temperatures. They should also be more compact and rugged than other pumps to withstand the harsh conditions of underground environments, such as varying fluid compositions, extreme flow, or abrasive particles. CFD can optimize the design and performance of tubing pumps by simulating fluid flow, pressure distributions, and various operating conditions.

CONVERGE offers several features that can simulate tubing pumps for oil and gas applications. FSI modeling can capture the motion of the stationary and traveling valves, which produce artificial lift and generate flow. The interactions between the solid valves and their respective seats can be simulated by CONVERGE’s contact model, while autonomous meshing can easily accommodate the valve motion while maintaining the integrity of the mesh.

Simulation of the flow of liquid hydrocarbons through a tubing pump using CONVERGE.

Erosion Modeling

Drill Bits

Drill bits are essential tools in various industries, particularly in drilling operations for oil and gas extraction, mining, and construction. They can be tailored for specific applications, such as penetrating different materials like rock, metal, or others. CFD plays a crucial role in optimizing drill bit performance by simulating fluid flow around the bit, debris clearance, and reducing wear. Further, by predicting thermal and erosion effects, CFD can help engineers refine drill bit designs, resulting in more efficient and cost-effective operations.

In CONVERGE, Lagrangian parcels are collections of solid, liquid, or gas particles. Liquid parcels are typically used for spray simulations, while solid parcels are very useful for drill applications in the oil and gas industry. For example, CONVERGE’s solid parcel modeling can simulate the erosion of gate valves due to sand in an oil or gas pipeline, sand ingestion in a gas turbine, sand blasting, and more. Other useful features in CONVERGE Studio include the custom case setup panels, which allow experienced users to create custom panels for various applications to highlight the most significant case parameters. This highly scriptable and user-friendly feature is particularly valuable for industries that practice division of labor, allowing teams with CFD expertise to set up simulations using the scripting tool and pass them onto other specialized teams, who can then easily extract the data needed to run those simulations.

Polycrystalline diamond compact (PDC) drill bits are popularly used in the industry due to their high durability, efficiency, and versatility. With CONVERGE, simulating these PDC drills can be done with powerful physical models, such as solid parcel, erosion, and conjugate heat transfer (CHT) modeling. CHT modeling can be computationally expensive because of the disparity in time scales between the heat transfer in the fluid and solid domains. To accelerate CHT simulations without sacrificing accuracy, CONVERGE offers super-cycling, which freezes the fluid solver periodically to allow the solid solver to progress to steady state. The fixed flow method is another available acceleration method that works particularly well for multi-stream simulations.

CONVERGE simulation of a PDC drill bit, with the drill head colored by temperature.

Digital Rock Simulation

CFD allows engineers to create a visualization of a real subterranean scan, which can then be used in mining applications, groundwater flow analysis, geothermal energy extraction, reservoir characterization and management, environmental impact studies, and more. CONVERGE’s porous media model can resolve the momentum and energy of flow through subterranean spaces. Temperature in the porous region may be predicted by the local thermal equilibrium (LTE) or local thermal non-equilibrium (LTNE) model. The LTNE model requires a source term proportional to the fluid-solver heat transfer coefficient (HTC).

Elbow Erosion

Elbow erosion can occur in piping systems due to factors such as high-velocity fluids, changes in flow direction, or abrasive particle characteristics. This erosion may then lead to thinning of the pipe, leaks, or even failure, resulting in increased maintenance costs and operational disruptions. CFD can help engineers analyze the fluid and particle flow dynamics within the elbow, predict erosion patterns, and optimize future pipe designs to reduce the rate of erosion-related complications.

To study elbow erosion in CONVERGE, users can employ the pressure-based PISO solver, which iteratively solves the transport equations at each time-step. Particle injections should be specified with two distinct flow rates, one for air and one for sand. Following the appropriate case setup, CONVERGE’s advanced turbulence and erosion models can effectively predict erosion rates.

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