COFAN THERMAL

DESIGN PROCESS

Four Stages of COFAN's CFD

The Cofan “CFD” process begins with an initial consultation or conversation with the client. During this Requirements stage of the process our client provides in-depth technical insight into their products and defines their goals and objectives as part of an in-depth discussion between the respective engineering teams.

It is during this phase that the Problem definition clearly defines the physical problem you want to study, including the geometry, boundary conditions, fluid properties, and other relevant parameters.

Pre-Processing

Stage 1

Processing

Stage 2

Post Processing

Stage 3

Validation / Verification

Stage 4

Stage 1

Pre Processing or Problem Definition Requirement

Required Input from the Customer

CAD Models of all Components, Hardware and Systems

Initial and Environmental Boundary Conditions

Thermal Performance Objectives

Fan Performances Curves

Power Levels of all components

Required Output from the CFD Study

Definition of project scope and deliverables

Phased timeline

List of Deliverables

Junction or Case Temperature of specified Components

Fluid flow conditions documentation

Reports, Design/engineering recommendations, databases, etc

Cost Breakdown

Stage 2

Processing or Solver Phase

This phase of the “CFD” is the stage where the numerical simulation is actually executed to solve the governing equations that describe fluid flow and related phenomena within a defined computational domain. This phase involves using a CFD solver, which is the specialized software program used by COFAN designed to implement the numerical methods required to solve these equations.  The solver iteratively calculates the flow and temperature fields over the computational mesh, considering the boundary conditions and fluid properties.

The processing phase can be computationally intensive, and the required time for simulation varies depending on factors such as the complexity of the geometry, the desired accuracy, the chosen numerical methods, and the computing resources available. Efficient processing often involves a balance between accuracy and computational cost, as well as careful consideration of solver settings and convergence criteria. The processing or solver phase is divided up into five steps:

Discretization

"Virtual" computational mesh is established that governs computational equations and how they are applied using numerical methods, such as finite difference, finite volume, or finite element methods.

Initialization

The initial set of conditions for the fluid flow, temperature distribution, pressure, and other relevant parameters within the computational domain, to mimic real-world starting state(s) of the system.

Time Stepping

Simulations can progress in "time steps", to better identify problems. At each time step, the solver re-calculates the flow and related properties over the computational mesh. The time step size is determined by factors like stability and temporal accuracy desired.

Solver Iterations

Repeated value updates of flow properties (velocity, pressure, temperature, etc.) across the entire computational mesh. The solver iterates until a certain convergence criterion is met, indicating a stable state or acceptable level of accuracy. 

Boundary Conditions

Boundary conditions are applied to the computational domain to reflect interactions between the system and its surroundings. Conditions include inflow, outflow, wall conditions, symmetry conditions, and more. 

Stage 3

Post-Processing Output or Analysis

After the simulation is complete, CFD post-processing tasks are performed.  These include extracting relevant data and involves analyzing, both qualitatively and quantitatively, the simulation predicted quantities. Visualization output of the simulation results obtained from the CFD simulation is the most effective manner to provides valuable insights into the behavior of fluid flow/patterns, temperature and pressure distributions/variations, and other relevant parameters of interest within the simulated system. 

It helps engineers gain a deeper understanding of fluid dynamics behavior within the system, relevant predictive temperatures of specific components, identify potential issues, and optimize designs for better performance. It also enables the communication of results to stakeholders and provides a basis for making informed decisions about system improvements or modifications. Some of the more common aspects of CFD post processing output includes the following:

Visualization

Contour Plots
Contour plots display variations of a specific parameter (e.g., velocity, pressure, temperature) across the computational domain. Color-coded contours help visualize gradients and trends.

Vector Plots
Vector Plots represent velocity vectors at different locations in the domain, indicating flow directions and magnitudes.

Streamlines
Streamlines depict the path that fluid particles follow within the flow field, providing a clear visualization of flow patterns.

Pathlines and Streaklines 
Showing the trajectories of individual fluid particles released at different points over time, helping to understand flow behavior over longer periods. 

Surface Plots
Surface Pressure Distribution: This plot shows the pressure distribution on the surfaces of objects within the domain, helping identify regions of high and low pressure. Heat Transfer Analysis: Surface temperature distribution plots provide insights into the heat transfer characteristics of the system.

Cut Planes and Slices 
These representations involve cutting through the computational domain to visualize internal flow structures, temperature gradients, or other properties along specific planes or sections.

Transient and Time-Averaged Data
For transient simulations, animations can be created to visualize the evolution of flow patterns over time. Time-averaged data helps understand the statistical properties of the flow, such as mean velocity profiles or temperature distributions.

Reports and Data Extraction 
Extracting quantitative data, such as maximum/minimum values, average values, or integrated quantities (e.g., mass flow rates), for specific regions of interest within the domain.
Generating reports that summarize key simulation results and findings.

Analysis of your system’s thermal flow behavior empowers informed design decisions, greatly enhancing  enhance system quality and reliability

Stage 4

Validation and Verification

Validating CFD simulation models is a crucial step to ensure that the numerical simulations accurately represent real-world physical behavior. Validation involves comparing the simulation results with experimental data or analytical solutions to assess the accuracy and reliability of the CFD model.

Data for simulation validation could come from any number of physical measurements in a controlled environment, such as wind tunnel tests, flow visualization techniques, thermocouple measurements or other relevant sources.  Overlaying the simulation results with experimental data provides one methodology to validate the accuracy of the simulation.

It’s important to note that perfect agreement between simulation and experimental data might not always be achievable due to uncertainties in both the simulation setup and experimental measurements. However, a reasonable level of agreement within acceptable tolerances demonstrates that the simulation model is reliable for its intended application.

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