Resolving Viscous Forces in CFD

What is the method used by FLUENT to evaluate the viscous forces (breakdown) on wall BC?

Answer 1

If you are simulating a flat plate at zero angle of attack then all the viscous forces will be along X(streamwise direction) and all the pressure forces along Y (normal to wall). But  for an aerofoil, there is a local slope for the wall at every point so in the global coordinates the shear forces will have x and y components. At every local point along the wall the shear force will be tangential to it and pressure forces normal to it. Since the aerofoil, generally. has a curvature with varying slopes there will always be x and y components for both shear and pressure forces.

If you are trying to calculate using viscosity*du/dy (here y is local wall normal coordinate not global y). If you use global coordinates then there is a component of viscous forces from x direction as well not just y.

Carefully accounting for components of forces from different directions at every local point along the aerofoil and then integrating for the whole system will resolve any ambiguities.

Who Made my Dish?

Who Made my Dish?
In recent days, i have a discomfort in my mind when starting to consume the food. The quality of the ingredients is bothering me on one side. On the other side, mind is questioning constantly whether the mood of the person who made the dish matters towards my health/welfare.
Another after thought is, Am i really qualified / worth for consuming that meal?
What great thing did i do, in order to have a delicious meal. I completely understood the items in my plate did not come just like that. What i am taking in, is the effort of so many creatures in this world right from the seed which transformed into plant then to bunch of seeds, the nature which provided the right nourishment, the farmer who did the right action, the merchant who made it available to buy, and  the cook who made it right for my tummy.
I remember one higher caste woman used to come to our house on business trips. She carries 5/6 meals in her bag. Never eats outside in hotel or even in our home. I thought it was because of caste discrimination that time. But now I started having a second thought. How to swallow something, which may not be right for my tummy. The contents of the food, the mood of the person who made it matters. Is it so?
I generally consume heavy meal / Tiffin when going to hotels. My mom used to comment on me when I was a kid. May be the dining table, brighter lights, bigger plates ,ghee roast dosa and 3 different chutneys might have made me to eat so. Even now my wife complains, how I get this much capacity only in hotel but not in home when taking buffet / unlimited meals.
I saw and see each cook as a divine personality, from my Grandmas, Chittis,Athais, Amma, Appa, friends, wife, hotel chefs and I.
I want to kiss them, hug them, fall on their feet and pray them since they made my tummy happy. Wait a minute. I have this much attachment on the people who made the food for me. What kind of attachment should I have got on the persons who helped in ensuring the food reaches my home, my market, the godown, and the farmer's effort.
I am not for sure ignorant, but negligent.

I am proud to say that I was/am not like few of my friends/colleagues and relatives who always overfill their plates in parties / marriage ceremonies. Finally, most of the items from their plates go to the rotten seepage. Is that for, it was made on first go?
Prizing the food and praying who enabled it to your plate, really make sense... Isn't it?
Still the question wandering in my mind, "Who made my Dish?"
- K Vijay Anand
- ‎17.11.17

The Curse of the Spider

The Curse of the Spider

I was cleaning my house meticulously ( ...which i never do unless a guest visit the following day).

I cleaned each and every corner of the floor as well as ceiling since tons of spider webs were all along the ceiling ( ...which i have never noticed earlier).
In that process, i noticed several spiders injured and even some of them were smashed to death. Many of the spider families were thrown at one go to the floor with my broom stick in hand.

My father used to tell me, 'Don't kill spiders ! In fact they are helping us by trapping the mosquitoes and other harmful flying insects'. But he will insist me to clean the webs once in a while in a months time. I never dared to ask him on this controversial aspect.

Now, coming back to the main story, the spiders were spread all along the floor in a very bad shape. I could sense their tears and agony.

The spiders were started yelling at me ... in fact cursing at me...
" We are living in this place for several generations in harmony and peace !  How cruel are you to demolish our nests and kill us !  Why did you do to us? What sin did we ever made to you ? "

I was astonished and got frozen. The only answer I could give to them was silence.

PS
When a heavy earth quake or Tsunami  strikes us, we don't know the equations behind. Several times, i asked Him, why me or why us?.
The only answer I could ever get was silence.
-K Vijay Anand
22-11-17       

The Invited and Uninvited

The Invited and Uninvited

Akhila was praying. She was sitting in front of Him. Tears were flowing like a waterfall.
She believed in Him. She wanted to comeout of the deep pains. In fact, she wanted to forget all her past. She meant, ALL HER PAST. The memories were not sweet for her. By now, betrayals wouldn't surprise her.
She couldn't close her eyes. Heart was very heavy and pounding. She wanted to share everything to someone. She desperately felt in need of a hug.
She wanted some warm shoulders to hide from herself.
All her mind was chanting repeatedly a single slogan, "Stupid, Stupid, Stupid, Stu....".
How idiotic was she?
What was her problem?
Why she wanted to get rid of the past?
Who gave her this agony?

Prabhu was thinking himself as the happiest in the universe. In short, he was a frog in the well.
He was sitting in front of Her. His face was quite  filled with joy. He believed in Her.
He accepted everything happened to him in the past. His needs were simple. All he wanted was his tummy to be filled. Whoever provided food to him, he took it happily.
All his pleasure was to eat and sleep. Occasionally, he thought about past. Sometimes about future too! But nothing could made him felt worried.
He always preferred to close his eyes and sleep. He looked life as a predetermined journey where he can't do much alterations.

And finally with the thundering bell sound in the temple, Akhila could close eyes now; felt light in heart; looked forward a peaceful life. All the blessings from Him were with her.
Prabhu opened up his eyes, rejoiced himself looking at Her eyes and started looking out where the temple Prasada was served. All the blessings from Her were with him.
-K Vijay Anand
30/11/2017