
Note that the divergence of the field is given by divF xFx + yFy + zFz y2 + z2 + x2 Now we can calculate the flux through the surface as a volume integral: SF dS VdivFdV Where V is the volume contained by surface S. (And, when we sum over tiny pieces of surface and take the limit of the Riemann sum, this approximation will become exact. 1 We can definitely use the divergence theorem in this problem.


Therefore, the circulation of a vector field along a simple closed curve can be transformed into a double integral and vice versa. In space, to have a flow through something you need a surface, e.g. This form of the theorem relates the vector line integral over a simple, closed plane curve C to a double integral over the region enclosed by C. Where V is the volume contained by surface S. In a plane, flux is a measure of how much a vector field is going across the curve. So, together we will learn why we use surface integrals and which form or formula to utilize when finding the flow rate across a surface. Now we can calculate the flux through the surface as a volume integral: SF dS VdivFdV. If the surface S is the graph of a function z f(x, y), oriented upward, and if F is a smooth vector field, then we can determine the formula as before.
Flux integral of vector field how to#
The surface integral of a function \(f\left( \right) d AĪnd together, we will learn how to use these formulas to evaluate the flux of a vector field across a surface in our video lesson. Let be a vector field defined on 3 that represents the velocity field of a fluid, and let be the density of the fluid.

Let’s take a closer look at each form of the surface integral. Line integrals over vector fields have the natural interpretation of computing work when F represents a force field. Here n is a unitary vector normal to the surface S and C is the curve.

Jenn, Founder Calcworkshop ®, 15+ Years Experience (Licensed & Certified Teacher)Ī line integral evaluates a function of two variables along a line, whereas a surface integral calculates a function of three variables over a surface.Īnd just as line integrals has two forms for either scalar functions or vector fields, surface integrals also have two forms: If F is a vector field defined along a curve C, the line integral (or work) of.
