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Enhanced Engineering Design by ANSYS Discovery for CFD Analysis

Summary

Engineers use Computational Fluid Dynamics (CFD) analysis to study and optimize fluid flow and heat transfer analysis in various applications. ANSYS Discovery is a user-friendly software platform that enables engineers to easily set up and solve CFD models and its ability to inform design modifications

In this blog post, we will highlight the advantages of using CFD analysis in Ansys Discovery for engineering design, which can help save time during the initial stages of product development. We will provide a detailed walkthrough of the process of setting up the model for fluid and thermal analysis, along with conducting the CFD simulation using ANSYS Discovery’s Explore and Refine modes. We will also discuss the meshing refinement process, emphasizing the similarities and differences between these modes. Furthermore, we will compare the capabilities of ANSYS Discovery in the Refine mode with those of ANSYS Fluent. Then, we will explore how to set up and use parametric studies in ANSYS Discovery. Lastly, we will delve into the conjugate heat transfer analysis for the fluid domain and the solid walls surrounding it. Each section will be accompanied by videos to provide clear examples and illustrate the concepts discussed.

1. Configuring an ANSYS Discovery CFD model

In this section, we will explore setting up a CFD model in the Model mode of ANSYS Discovery. Firstly, we choose a pre-built example and modify the geometry to fit our needs. After that, we inspect the geometry for errors and defects, make necessary repairs using Discovery Design tools, and extract the volume from the solid model to define the fluid domain. Next, we specify the boundary conditions, such as inlet and outlet velocities, temperatures, and pressure, and set the physics of the problem by choosing the fluid material, specifying the fluid properties, initial temperature, etc.

2. Solving CFD Model in ANSYS Discovery: Explore Mode

There are two modes available in ANSYS Discovery for solving CFD models: Explore and Refine. In Explore mode, we can obtain an initial solution quickly, gain a general understanding of the flow behavior, and identify any potential issues or areas for improvement.

We will run the CFD model and show you how to perform basic post-processing tasks and visualize the flow patterns, velocity distributions, and temperature gradients in the domain by generating contour plots, vector animations, and streamlines. This will allow us to gain insights into the flow behavior and identify any regions of high mixing, recirculation, or heat transfer.

3. Mesh Refinement in Explore mode

To enhance the accuracy of our initial solution in Explore mode, we can refine the mesh used for geometry discretization and solving CFD equations. The level of refinement depends on the desired accuracy and available computational resources.

In this model, we use some meshing features, such as Global Fidelity and Size Preview, to improve the mesh quality across the domain. We conducted a mesh study to understand how mesh density and element size can impact the results, such as mixing hot and cold water and determining the maximum velocity and temperature in the domain.

4. CFD Model Improvement: Refine Mode

 

The Refine mode ANSYS Discovery can be used to improve the accuracy and detail of CFD models and obtain more precise results than using the Explore mode.
Local mesh refinement can be achieved by using Local Fidelity, which allows us to focus on specific parts of the domain we are interested in and obtain more accurate flow behavior there. We can also control the meshing schemes of the domain regarding curvature and proximity, which can increase the reliability of our simulation, particularly when predicting values such as pressure drop or heat transfer. In this mode, mesh information is accessible for mesh elements and nodes, as well as mesh quality indicators such as mesh orthogonality and aspect ratio.

Using the refine mode, we have more control over the solution by selecting turbulent models, setting convergence criteria, changing the residuals, and setting the time step in the transient simulation, among other things. Moreover, GPU computation is available in both Explore and Refine modes in the ANSYS Discovery 2023R2 version. Additionally, ANSYS 2023R2 offers both tetrahedral and polyhedral meshing options. The Refine mode in ANSYS Discovery can offer highly accurate CFD simulation results that are comparable to those obtained from ANSYS Fluent and CFX. However, the ANSYS Discovery solution is much faster and simpler to set up when compared to other CFD solvers in ANSYS.
Overall, the Refine mode in ANSYS Discovery enables us to fine-tune CFD models, achieve higher levels of accuracy, and gain more confidence in the results we obtain. This can significantly accelerate the engineering design and product development processes.

 

5. Parametric Study and Design Modification

Using ANSYS Discovery’s Explore mode can provide a quick and intuitive solution to help make informed design decisions about CFD models. Additionally, we can use the Explore mode to perform sensitivity analysis by changing input parameters and inspecting their impacts. This allows us to optimize the design and identify key parameters affecting fluid flow and heat transfer behavior.

We can use a parametric study to identify areas for improvement and make design changes to optimize the performance of the CFD model. In our parametric study, we adjust boundary conditions such as flow velocity and temperature, as well as geometrical features of the model, as key parameters in our CFD model. We build test cases with a series of these parameters and check the improvement of the mixing process in the CFD model. It’s important to note that geometry modification is impossible inside ANSYS Fluent and CFX, so we need a separate CAD modeler tool, such as SpaceClaim, to make the changes. Then we can return the model to the ANSYS CFD solver to set up and solve the new models. However, with ANSYS Discovery, we can make all changes to the geometry and physics of the problem together inside the program, which is a huge advantage. We don’t need to exit the program, and everything is integrated and developed inside Discovery.

Once we gain insights from the analysis, we can modify the geometry, adjust the boundary conditions, or optimize the system components to achieve the desired performance goals. This iterative process allows us to fine-tune our designs and achieve optimal results.

6. Conjugate Heat Transfer Analysis

In the last section, we explore the heat transfer in the fluid domain and the surrounding solid bodies by conjugate heat transfer analysis. We include thermal boundary conditions for the elbow walls, in addition to the fluid and thermal conditions already assigned to the fluid domain. We first apply the heat flow condition to the solids, explain the setup for conducting conjugate heat transfer in Ansys Discovery, and then solve the model and show the results in Explore mode. Then, we study the impact of introducing new material and new heat conditions in the solids, utilizing the monitors embedded in Discovery analysis to analyze the effects; we change the wall material to copper alloy and subsequently add insulation, observing how these modifications influence the results. we wrap up this part by showcasing the setup and solving of the model in the Refine mode to provide a comprehensive exploration of conjugate heat transfer analysis in Ansys Discovery.

By harnessing the power of ANSYS Discovery, we can unlock the potential to transform the design process, creating fluid and thermal products that are not only efficient and reliable but also truly innovative.