Saturday, 9 December 2017

Computational Fluid Dynamics - software and materials


 Hi friends,

Are you interested in computational fluid dynamics simulations? 

If you are a beginner, let me introduce you various software/tools available now and reference materials for learning them. This may help you to know most of the possible options you have to start with your CFD simulation work.

Prerequisites for CFD analysis:
  1. Fundamentals regarding the phenomena to be analyzed viz. Fluid mechanics, Turbulence, Heat transfer, chemical reactions, phase change processes etc as per the requirement I love the text book by Yunus A. Cengel in this aspect
  2. Theory behind CFD analysis. Discretization models, solution methodologies, various solvers. Good references for these aspects are the books by Andersen, Patankar, Malalasekhera, Ferziger and Peric  The user guide and theory guides of various CFD software also help in software specific implementation of various models. Lectures of Lorena A Barba
  3. Software package installed in PC

There are various software and tools available for CFD analysis in both commercial and open source domains.

Commercial CFD solvers:
  1. ANSYS FLUENT
  2. ANSYS CFX
  3. ANSYS POLYFLOW
  4. Hyper works AcuSolve
  5. PHOENICS
  6. STAR CCM+ 
  7. COMSOL Multiphysics and many more
Open source CFD solvers:
  1. Open FOAM
  2. SU 2 etc
 Code yourself: 
 You can write your own codes for the problems you want to solve. There are various research groups which are taking initiatives for the same, CFD - Open Source. 
  1.  Lorena A Barba group link 
  2.  Chalmers university of technology link
  3.  Open FOAM itself gives that opportunity (custom codes can be written in C++ language and added to Open FOAM package). 
Pre and post processing tools:
For setting up the CFD problem, one requires to define the domain (in terms of geometry) and corresponding grid (also called as mesh). Once the results are obtained from the solver, they can be visualized using various tools. Following is the list of various tools available for the purpose

Commercial:
  1. ANSYS Design modeler
  2. ANSYS Meshing
  3. ANSYS ICEM CFD
  4. Gambit
  5. Solid Works/Pro E/CATIA/Rhinoceros etc CAD software for geometry preparation
  6. Hyper Mesh
  7. Pointwise 
  8. TGrid and more
Open source:
  1. Salome
  2. Gmsh
  3. TetGen
  4. Open FOAM blockMesh, snappyHexMesh
  5. enGrid and more

Tutorials and materials:
Tutorials for various software and tools given above are widely available online now-a-days. Some of them are given here for reference.



Resource
Software/tool
Link
Cornell university
FLUENT
https://confluence.cornell.edu/display/SIMULATION/FLUENT+Learning+Modules
Learn CAx
FLUENT, CFX, GAMBIT, ICEM CFD, TGrid, Solid Works, STAR CCM+,
https://learncax.com/courses
FLUENT
FLUENT
Open FOAM (ESI group)
Open FOAM
https://www.openfoam.com/documentation/tutorial-guide/
Chalmers university
Open FOAM
Source forge
Open FOAM
http://foam.sourceforge.net/docs/Guides-a4/OpenFOAMUserGuide-A4.pdf
-
ANSYS Meshing
Next Foam
Open FOAM Boundary conditions



 Many more material would be available online. Based on the requirement, one can search and get. If nothing is found for your application, try to do it with help of your guide/friends. But, do not forget to share your expertise online. Gift your experience. And also do not forget to share your link in comments below.


Discussion forums:
If you have any queries regarding any of the CFD software you can post threads at http://www.cfd-online.com 

Please drop your comments below for improving this post.




Author info:

Saikrishna Nadella
B.Tech (Mechanical engineering)
Rajiv Gandhi University of Knowledge Technologies, AP IIIT, Nuzvid 521202.

Experience in CFD: 
  1. CFD Simulation of transscleral drug diffusion in human eye. Phenomena/models: laminar flow, species transport, time varying boundary conditions, flow through porous medium
  2. CFD simulation of foldable passive solar dryer. Phenomena/models: buoyancy driven flow, solar ray tracing, drying of food and moisture transport, flow through porous medium
  3. CFD simulation of transient fluid flow in packed columns. Phenomena/models: VOF model, flow through porous media, 
  4. Finite difference code for transient fluid flow simulation in packed columns 
  5. FEM simulation of electromagnetic induction melting. Phenomena/models: coupled heat transfer and electromagnetics, melting and solidification
  6. CFD simulation of rotating disk in fluid filled vessel: Phenomena/models: RSM turbulence model, moving wall boundary conditions
  7. CFD simulation of pressure pulse propagation in pipe (going on). Phenomena/models: transient boundary conditions, pressure dependent density
  8. CFD simulation of two phase adiabatic and boiling flows (going on). Phenomena/models: Euler two phase model, boiling models, interface transport models, turbulence models for multiphase flows.
  9. Finite difference code SiPhN(TA) for transient simulation of natural circulation loops

Friday, 4 November 2016

Understanding Material behavior - material science learning made interactive,

Dear friends,

  Are you wishing to take a course on material science? For any field of engineering, material science is an important thing to get acquainted with in the current scenario of stingent property requirements.

 Now-a-days a bunch of online courses are available for learning various science and engineering topics. Similar case for material science as well.

 Recently I found a nicely organised interactive course content for material science in university of Cambridge website.

Link : http://www.doitpoms.ac.uk/tlplib/index.php

"Teaching and learning packages (TLPs) are self-contained, interactive resources, each focusing on one area of Materials Science."

This will be very useful for students, practising engineers as well as teachers.


Besides this,

There are courses in edx.org in which comprehensive material is given for different subtopics in material science. If course is not ON, you can audit the content/go through archived material.


Thank you.

Wednesday, 6 April 2016

BARC OCES/DGFS recruitment interview questions - Part 2

Hi,
I am glad to share some more questions asked in BARC OCES/DGFS recruitment interview for mechanical engineering discipline in 2015. These questions were shared by my colleague.
1.       Draw the shear force and bending moment diagrams for the following beam subjected to point load at the mid span. (Ref fig.1)

2.       In the above problem, replace the beam with a rope and draw the SFD & BMD. Which one will have more strength and Why? (Ref fig.1)
3.       What is the required load ‘W’ to be applied in order to make θ zero degrees? (Ref fig. 2)

 
Fig. 2

4.       Two steel balls, one is of volume V and the other is of volume 2V. Both contains same amount of sensible thermal energy 2000J in them. Which will have more temperature?
5.       Two spherical bodies of same diameter D, are connected by a string as shown in fig. 3. If the string is in tension, can both be of same material? Determine the weights of the two bodies. (Ref fig.3)

6.       For the bar shown in figure below, assuming 1-D axial heat conduction and completely insulated boundaries around and subjected to same temperature 1000 K at the ends at time t=0. If the initial temperature of the bar is 300K, draw the temperature profile along the length, at some typical instances for t>0. (Ref fig.4)
7.       There are two vessels, A and B, having same diameter and containing water to the same level. But one vessel has steel ball in it and they are heated from bottom at the same time. Draw the approximate average water temperature variation in them with respect to time. Does both require same amount of time to start boiling under same ambient pressure conditions? If not, which one requires more time? (Ref fig.5)

8.       For a reversible Carnot engine, find the relation between temperatures TH, TC and heats QH, QC.
9.       Tell all the laws of thermodynamics with application for each law.
10.   How can you find whether scaling occurred on condenser tubes or not?
11.   Draw the temperature profiles for shell side and tube side fluids for a typical condenser.
12.   What is the stress in the below bar subjected to force P1 at one end and force P2 at other end? (Ref fig.6)


All the very Best.!!!