Gadia Pranamya Adhikaputra
This is my home page.
Perkenalkan, saya Gadia Pranamya Adhikaputra dari Fakultas Teknik Program S1 Teknik Mesin Reguler angkatan 2020. Salah satu interest saya dalam program ini adalah dalam pengaplikasian mata-mata kuliah yang telah dipelajari dalam skala kecil/personal.
One application of CFD I have grown an interest in is in the analysis of an airflow in a room. Though my plan currently is only to analyze my bedroom, this technology may be used in larger scale projects (one room I have in mind is a certain area in a certain shopping mall that has ridiculously poor air circulation.)
I have gathered a few questions I may need answers of whether I'm going to look for them myself or by asking others:
1. How do I even use the CFD programs?
2. How do I accurately model a room and load it into my selected CFD program?
3. If I even DO solve the above 2 questions, what will I even do with said information?
Answers may come later.
The DAI5 Conscious Thinking Framework
The DAI5 framework is a thinking framework devised by yours truly, to help with tackling complex and/or difficult tasks by breaking it down and looking past the surface in an attempt to intuit the intention of the issue and understand it on a deeper level. The steps are comprised of:
- Intention
- Initial Thinking
- Idealization
- Instruction Set
Despite the name not matching the number of steps, the 5th "I" lies in the author as the Initiator.
While this part of the article seems rather thin, I have condensed the majority of meaningful contents into this video presentation about said thinking framework. You can watch the video here:
LID-DRIVEN CAVITY
A benchmark problem in CFD, used to determine how valid a certain method/program is for doing fluid analysis. More details will be added once I figure out how to upload pictures on this thing.
MIDTERMS RESULTS
Everything listed below is ChatGPT's evaluation of my answers to the questions it has asked.
1. What is Lid-Driven Cavity Flow, and why is it commonly used as a benchmark problem in CFD? Your Answer: Lid-Driven cavity flow is a common problem for CFD programs that involves 3 no-slip walls (assuming 2 dimensions) and a lid that moves at a tangential velocity in one direction. It is commonly used as a benchmark due to how it visualizes the properties of incompressible fluids.
Feedback: Good explanation of the setup with clear emphasis on the no-slip boundary condition and the moving lid. You’ve captured why it’s useful for visualizing incompressible fluid behavior.
Grade: 9/10
2. Explain the boundary conditions applied in a Lid-Driven Cavity Flow simulation. What role does the moving lid play in the flow field? Your Answer: There are 3 no-slip walls of equal length and a moving lid. The moving lid introduces movement into the flow field to simulate how water would move when given a force.
Feedback: You correctly describe the boundary conditions, but the role of the moving lid could be elaborated more. It’s responsible for generating the primary flow and setting up the vortex structures within the cavity, and the answer would benefit from this detail.
Grade: 7.5/10
3. Describe how the Navier-Stokes equations are applied in simulating Lid-Driven Cavity Flow. Your Answer: The Navier-Stokes equations describe how fluids move within a space, so they are mandatory for achieving any result in Lid-Driven Cavity Flow simulation.
Feedback: You capture the fundamental importance of the Navier-Stokes equations, but it would be helpful to mention that these equations account for conservation of momentum and mass in the flow. A brief mention of how they handle viscosity, pressure, and velocity fields would add depth.
Grade: 7/10
4. What numerical methods are typically used to solve Lid-Driven Cavity Flow problems? Revised Answer: The numerical methods used in CFD for simulating Lid-Driven Cavity Flow help in discretizing the mesh and solving the fluid dynamics equations. The Finite Difference Method (FDM) is commonly used to calculate how fluid moves over a grid by approximating the derivatives in the Navier-Stokes equations. For example, FDM is widely used in problems like heat and mass transfer to compute how heat or fluids behave over time. Similarly, the Finite Volume Method (FVM) divides the domain into small control volumes and applies conservation laws across each volume. The Finite Element Method (FEM), on the other hand, breaks down the domain into elements and solves the governing equations over these elements using interpolation functions.
Feedback: This is a much more complete and accurate answer. You've correctly introduced FDM, FVM, and FEM as methods for discretizing and solving the fluid dynamics problem. You’ve also explained how FDM can be applied to both heat transfer and fluid dynamics, which demonstrates an understanding of its versatility. Mentioning the principles behind FVM and FEM rounds out the explanation well.
Grade: 9/10
5. Discuss the importance of mesh refinement in Lid-Driven Cavity Flow simulations. Your Answer: Mesh refinement is important because the mesh must accurately reflect how the object would perform under real-life situations.
Feedback: You correctly point out that mesh refinement increases accuracy, but you could elaborate on how a finer mesh leads to better resolution of flow features, especially in regions with high velocity gradients, like near walls or vortex cores.
Grade: 7.5/10
6. In a Lid-Driven Cavity Flow problem, what is the significance of the Reynolds number? Your Answer: The Reynolds number is a ratio of Fluid Inertia to the Dynamic Viscosity. The flow becomes more violent as the Reynolds number increases.
Feedback: This is mostly correct. The Reynolds number is indeed a ratio of inertia to viscosity and indicates the flow regime (laminar or turbulent). You could further explain how low Reynolds numbers correspond to smooth (laminar) flow, while high Reynolds numbers result in chaotic (turbulent) flow.
Grade: 8/10
7. What challenges might arise when solving a Lid-Driven Cavity Flow simulation for high Reynolds numbers? Your Answer: High Reynolds numbers introduce more vortexes into the system, usually forming within the corners of the no-slip walls.
Feedback: You correctly note that vortex formation becomes more complex at high Reynolds numbers. Additional challenges include numerical stability, resolving fine flow details, and requiring more refined meshes and time-stepping methods.
Grade: 7.5/10
8. How can the velocity profile of a Lid-Driven Cavity Flow be visualized? Your Answer: There would be a large vortex in the center and multiple vortex flows in the corners of the no-slip walls.
Feedback: This answer is accurate but could be expanded. The velocity profile is often visualized through streamlines or velocity vectors, showing primary and secondary vortex structures depending on the Reynolds number.
Grade: 7/10
9. Explain how convergence is monitored in a Lid-Driven Cavity Flow simulation. Your Answer: Convergence is monitored by comparing results from one time step to the previous one, and the program stops once the difference is within a defined threshold.
Feedback: This is a good basic description of convergence. You could mention the role of residuals (errors in solving the discretized equations) and how they decrease as the solution converges.
Grade: 7.5/10
10. Give an example of how Lid-Driven Cavity Flow simulations can validate numerical methods in CFD. Your Answer: Lid-Driven cavity flow simulations can be used to validate numerical methods by comparing results with peer-reviewed studies or publications.
Feedback: Good answer! It shows an understanding of validation practices, though it would benefit from specific details about what flow characteristics (e.g., velocity, pressure, or vortex patterns) are often compared.
Grade: 8/10
