Ujian Tengah Semester Komputasi Teknik (Midterm Engineering Computation)

1.      Write and explain step engineering solutions with a computational approach

a. Problem analysis
Obtain as much information about all the problems that may arise that affect the strength of the design structure of an object as an example:
The influences of environmental (wind direction and speed (aerodynamics), humidity, around the area of object,etc)
The Influence of loading (static and dynamic conditions, the dimensions of design objects (length.witdh, high), mass of design objects, etc.)
The influence of the power structure (the choice of material, type of solid / hollow, bending strength, dimensional material, diameter, the size of the iron column foundation, strength of welded/ rivet )

b. List Assumption
Making assumptions supporting the calculation such steady / unsteady, in 2D/3D analysis, static conditions / dynamics, flow direction from the direction of U, V, W (free stream)

c. Develop appropriate model
Makes modeling of the geometry that represents the object to be calculated both mathematical concept drawings and models

d. Run the Model
Running the model in  simulation program with a variety of input data and constraints, how many times the iterative process of calculation to obtain convergence results

e. Check the model of result / execution / simulation
See the results of the simulation calculations trend is approached by mathematical analysis and calculation error is very small errors or tend to converge (as a result of the validation)

f. Conclusion and recommendation
When the results of the validation are correct, it can be inferred through the process of simulation calculations and can be recommended for the next phase (phase engineering / construction, prototype, optimization)


2. The concept of computational algorithms

The concept of computational algorithms is a sequence of logical steps needed to solve a problem-solving with some of the data that is input by using a computer assisted. In this case the algorithm is distinguished between the sections of data and section of instruction. Instruction section consists of sequence instructions are executed one by one in sequence by processing. The flow of Instruction execution can be changed due to conditional branching. The data stored in the memory manipulated by instruction in a sequence. So it can be illustrated that the algorithm is a flow diagram / flowchart to get the solution of a problem.
For example, to search for Lagrangian interpolation points between 3 pieces of point P1 (x1, y1), P2 (x2, y2), P3 (x3, y3) with a quadratic function approach

The algorithm of Interpolation Lagrangian:

1. Determine 3 input  of point P1 (x1, y1), P2 (x2, y2), P3 (x3, y3)
2. Determine the value of x from the point to be searched
3. Calculate the y value of the point to be searched by formula of Lagrangian interpolation
4. Show the value of x and y

3. Modeling what it is? Illustrate with an example of simulation and computational models

 
The model is a simple geometric shape images that have a certain scale of geometric shapes that represent the actual / original to the next in a specific simulation run the program with different inputs and constraints in order to obtain the results of the calculation approach of simulation againts to the model.
For example, to calculate the pressure drag on the billboard, then the process is illustrated with wind tunnel testing to calculate how the pressure drop on the billboard. For it made a modeling ​​with a picture that represents the bilboard and the wind tunnel at a certain scale in the simulation program.

Illustration models billboard:

                                     billboard 3-dimensional                Billboard 2-dimensional side view  

Billboards with size:
Width              : 2 m
Thickness        : 10 cm
given static air flow at the front (INLET) with velocity (v) coordinate direction U: 5 m / s

Wind tunnel with size:
length              : 26 m
height              : 6 m
so that when the program is made on CFD modeling

Wind tunnel models
Cell allocation: 25000
Domain: I = 260 cell (length = 26 m wind tunnel)
              J = 60 cell (wind tunnel height = 6 m)
The size of each cell: 0.1 m (1:10 scale cell)

Billboard Model:
Width  = 1 cell (10 cm) in the 50-51 cell
Height  = 20 cell (2 m) in the 20-40 cell

assumptions:

• pole buffer board negligible (considered thd airflow dynamic pressure is very small)
• steady state conditions
• Analysis in 2D
• properties are considered constant

Boundary settings:
Upper & lower boundary = SIMETRY
Front boundary= INLET
Rear boundary = OUTLET 
Model Billboards = W-WALL

On the Sempadan Conditions (KS) static velocity setting direction U = 5 m / s section INLET.
Process of iteration = 500
Results visualization display velocity and pressure