Cauchy's equation in terms of material acceleration

In summary, the equation in question is a dot product of del and rho*a 2nd order tensor(V V), and can be solved using the derivative of a product rule in cartesian component form. It is related to transforming Cauchy's equation in terms of material acceleration.
  • #1
Adam Venter
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Does anyone know which formula is used or how to arrive at the righthand side of the equation below, which is the dot product of del and rho*a 2nd order tensor(V V).
. represents dot product
and X a vector quantity
This problem is in connection with transforming cauchy's equation in terms of the material acceleration

del . (rho*V V) = {V*del . (rho*V) } + {rho*(V . del)*V}

Thanks
 
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  • #2
Adam Venter said:
Does anyone know which formula is used or how to arrive at the righthand side of the equation below, which is the dot product of del and rho*a 2nd order tensor(V V).
. represents dot product
and X a vector quantity
This problem is in connection with transforming cauchy's equation in terms of the material acceleration

del . (rho*V V) = {V*del . (rho*V) } + {rho*(V . del)*V}

Thanks
It's basically application of the derivative of a product rule in a situation in which you are dealing with vectors. The easiest way to prove to yourself that the identity is correct is to write it out in cartesian component form.

Chet
 
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  • #3
Chestermiller said:
It's basically application of the derivative of a product rule in a situation in which you are dealing with vectors. The easiest way to prove to yourself that the identity is correct is to write it out in cartesian component form.

Chet
Thanks will give that a go
 

1. What is Cauchy's equation in terms of material acceleration?

Cauchy's equation in terms of material acceleration is a fundamental equation in fluid mechanics that relates the material acceleration of a fluid element to the forces acting on it. It is represented as Du/Dt = F/m, where u is the material acceleration, Dt is the material derivative, F is the sum of all forces acting on the fluid element, and m is the mass of the fluid element.

2. How is Cauchy's equation derived?

Cauchy's equation is derived from Newton's second law of motion, which states that the net force acting on an object is equal to its mass times its acceleration. By applying this law to a fluid element, we can derive Cauchy's equation and understand how forces affect the material acceleration of the fluid.

3. What is the significance of Cauchy's equation in fluid mechanics?

Cauchy's equation is significant because it allows us to analyze the motion of fluids and understand the forces that influence their behavior. It is used in various applications, such as aerodynamics, hydrodynamics, and weather forecasting, to predict the movement and behavior of fluids.

4. Can Cauchy's equation be applied to all types of fluids?

Yes, Cauchy's equation can be applied to all types of fluids, including gases and liquids. It is a fundamental equation in fluid mechanics and is valid for all types of fluids, as long as the fluid is incompressible and the flow is steady.

5. How does Cauchy's equation relate to Bernoulli's equation?

Cauchy's equation is a more general form of Bernoulli's equation, which is a simplified version that applies specifically to fluids in motion. Bernoulli's equation assumes that the fluid is inviscid (no internal friction) and incompressible, whereas Cauchy's equation takes into account the effects of viscosity and compressibility on the fluid's material acceleration.

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