Материал: Homework_1_(Electrostatics)_What_to_do
Anyway, before starting the Capacitance wizard you have to define the contour for charge integration as described above.
Next to the introductory page the Capacitance wizard offers a window for choosing the conductor of interest
26
,
On the next page we have to click the contour in the list on the top and press the button Calculate Energy. As result both integrals needed for capacitance – the charge and the energy, gets calculated.
Click the Next button leads to the results page:
27
Ideally both capacitance values calculated by charge and by energy should be very close to each other. The significant difference may indicate a methodical error. Because the mode employs symmetry it is a good idea to think about possible symmetry factor.
3. REPORT CONTENT
Please start your report with a cover page containing your name and group number, the project name, and the current year.
The report may be organized in the following way:
Report content:
1.Task description and the given data
2.Sketch of the geometry model with no mesh
3.Dependency of maximal field Emax on the mesh spacing on the rounded capacitor’s corner.
Please provide at least 5 points up to the convergency of EMAX = f(spacing). The dependency should be presented in the form of a table and an XY-plot.
4.Pictures with the mesh and E-field around the rounded end of the conductor:
4.1With the initial (automatic) mesh spacing
4.2With the final mesh spacing
5.Choose an optimal mesh spacing on the conductor from the previous research and investigate the dependency of EMAX on the radius R0 of the artificial outer boundary until the convergency
28
is achieved. Start with the small radius, e.g., twice the half-width of the conductor, and continue increasing it while the field EMAX keeps changing.
6.The rest of calculation please do only once with the final mesh spacing and the final value of the radius R0.
7.Calculate the capacitance:
-Cth by a simple formula (theory of a plane capacitor)
-Cq using charge
-Cw using energy
8.Calculate the field in the middle of capacitor Ec
9.Please submit your work by email to sdubitsky@gmail.com . Include your report (Word or PDF) and all QuickField files related to the final mesh density and final position of the outer boundary.
4.FINAL DEFENSE
Please be prepared to explain how and why you have set up the boundary conditions, especially the boundary conditions due to symmetry.
You may be asked to explain in detail how you do the integration for charge and energy, including what is the domain of integration and what formula was used.
Think about possible symmetry factor to jump from the one quarter to the entire model.
An additional question you may be asked is how to calculate the mechanical force acting on the capacitor’s plate.
29