Basic understanding of CFD

CFD

This post is a simple understanding of CFD. Don’t skip anything and read the post fully.

CFD is said to be Computational Fluid Dynamics. CFD comprises of fluid dynamics, physics and maths.

It is the computational representation of fluid flow and numerical aspects of the given component.

Who can learn CFD?

The person who is interested in understanding the fluid around environment effects the pressure, velocity of any particular component and strong in fluid dynamics, thermodynamics, and heat transfer.

     

Applications of CFD:

It is mainly used in the following streams:

·      Aerospace analysis.

·      IC engine stimulation.

·      Weather stimulation.

·      Marine design and offshore analysis.

·      Medical fields.

·      Structural analysis (construction of buildings, dams etc.)

·      Refrigeration and air-conditioning.

Job roles in CFD:

·      CFD Analyst/ CFD Engineer (Meshing & Solver roles).

·      CFD Software developer.

CFD tools:

Some of the common CFD tools are ANSYS fluid, Star CCM+, Converge. The high level way or tools used for governing problems are MATLAB & Python. 

Why CFD is very important?

CFD is the very cheap stimulation method compare to other method. It is the most important technique to stimulate fluid flows using a computer and analyse data structures of the model. It helps for undergoing research and further understanding the surface boundary conditions. More complex equations can be solved by CFD accurately by using super computers with high speed.

The companies perform more experiments and validate the design and analyse the test results.

But the disadvantage of CFD is, the obtained result can be 70% accurate.

Important equations in CFD:

Special equation Navier–Stokes can be solved easily.

Navier-Stokes equation for Conservation of Momentum for a fluid element is expressed below:

Continuity: ∂ρ/∂t+∂ (ρu)/∂x+∂ (ρv)/∂y+∂ (ρw)/∂z  =0

X-Momentum:
 

∂(ρu)/∂t+∂(ρu^2)/∂x+∂(ρuv)/∂y+∂(ρuw)/∂z =−∂p/∂x+∂/∂x(𝜆 𝛥 ·𝑉⃗ +2𝜇 𝜕𝑢/𝜕𝑥)+∂/∂y[μ(∂v/∂x+∂u/∂y)]+∂/∂z[μ(∂u/∂z+∂w/∂x)]+ρfx

Y-Momentum:
 

∂(ρv)/∂t+ ∂(ρuv)/∂x+∂(ρv^2)∂y+∂(ρvw)/∂z =−∂p/∂y+∂/∂x[μ(𝜕𝑣/𝜕𝑥+∂u/∂y)]+∂∂y(𝜆 𝛥 ·𝑉⃗ +2𝜇∂v/∂y)+∂/∂z[μ(∂w/∂y+∂v/∂z)]+ρfy

Z-Momentum:
 

∂(ρw)/∂t+ ∂(ρuw)/∂x+∂(ρvw)/∂y+∂(ρw^2)/∂z =−∂p/∂z+∂/∂x[μ(𝜕𝑢/𝜕𝑧+∂w/∂x)]+∂/∂y[μ(∂w/∂y+∂v/∂z)]+∂/∂z(𝜆 𝛥 ·𝑉⃗ +2𝜇∂w/∂z)+ρfz

Energy:

ρ𝐷/Dt(𝑒+𝑉^2/2)=ρq+∂/∂x(𝑘∂T/∂x)+∂/∂y(𝑘∂T/∂y)+∂/∂z(𝑘∂T/∂z)−∂(up)/∂x−∂(vp)/∂y−∂(wp)/∂z+∂(uτxx)/∂x+ ∂(uτyx)/∂y+∂(uτzx)/∂z+∂(vτxy)/∂x+∂(vτyy)/∂y+∂(vτzy)/∂z+ ∂(wτxz)/∂x+∂(wτyz)/∂y+∂(wτzz)/∂z+ρ𝑓 ·V

These equations are set of partial differential equations coupled and non-linear.These equations are written in the form of matrix and the values for U,V,W,P and T are obtained.

The above figure represents the solution of Navier-Stokes equation by CFD method.

Guest blogger :

I'm harish, a mechanical engineer by profession and a  blogger by passion.

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