InterviewSolution

Explore topic-wise InterviewSolutions in .

This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

51.	The direction of the normal to a face in an unstructured mesh depends upon __________(a) Local indices(b) Global indices(c) Direction of flow(d) Direction of increasing indicesI had been asked this question in quiz.This intriguing question originated from FVM topic in chapter Finite Volume Methods of Computational Fluid Dynamics
Answer» Right option is (b) Global indices Explanation: The DIRECTION of the NORMAL to a face DEPENDS on the indices in both STRUCTURED and unstructured grids. For structured grids, it depends on the direction of increasing indices. For unstructured grids, the direction depends on the global index NUMBER.

52.	I know the value of flux at point xc. How will you find the value of this flux at point x away form xc?(a) Simpson’s rule(b) Trapezoidal rule(c) Mean value theorem(d) Taylor series expansionThis question was posed to me in examination.Origin of the question is Finite Volume Methods in chapter Finite Volume Methods of Computational Fluid Dynamics
Answer» The correct ANSWER is (d) Taylor series expansion The explanation is: SIMPSON’s rule, Trapezoidal rule and the Mean value theorem are all used to integrate a function numerically. To GET a value at the point near ANOTHER point where the value is known, we use the Taylor series.

53.	Which of these three-dimensional elements has faces as a mixture of two shapes?(a) Tetrahedron(b) Prism(c) Hexahedron(d) OctahedronI had been asked this question in quiz.The origin of the question is Types of FVM Elements topic in section Finite Volume Methods of Computational Fluid Dynamics
Answer»

54.	The values of the flow variables at the faces can be calculated by _____________ in a structured grid.(a) Interpolation(b) Taylor series(c) Fourier series(d) Shape functionsI have been asked this question in an international level competition.My doubt is from FVM topic in chapter Finite Volume Methods of Computational Fluid Dynamics
Answer» The correct choice is (a) Interpolation Explanation: As the CELLS of a structured grid have simple quadrilateral SHAPES, the values at a cell faces can be EASILY interpolated using the values of the flow VARIABLES at the cell centroids of the TWO cells sharing that particular face.

55.	Dual cell or dual mesh method is used to __________(a) create boundary elements(b) create elements around a vertex(c) create cell-centred arrangement(d) create boundary facesThe question was asked at a job interview.The query is from Variable Arrangement in FVM topic in chapter Finite Volume Methods of Computational Fluid Dynamics
Answer» Correct CHOICE is (b) create elements AROUND a vertex The explanation is: In the vertex-centred arrangements, elements are created around the vertices by JOINING either their centroids or their centroids with the face-centroids. This method of forming the vertex-centred arrangement is called dual cell or dual mesh method.

56.	Simpson’s rule assumes the function to be ___________(a) constant(b) cubic(c) linear(d) quadraticI have been asked this question in unit test.My question is from Finite Volume Methods in chapter Finite Volume Methods of Computational Fluid Dynamics
Answer» The correct answer is (d) quadratic To explain I would say: Simpson’s RULE ASSUMES the FUNCTION to be integrated as a quadratic function. The points chosen to generate the quadratic LINE are the two endpoints and the midpoint. So, this APPROXIMATION is more accurate.

57.	Which of these statements is true for unstructured grids?(a) It is simple to model and use(b) Element connectivity is implicitly defined(c) Element connectivity does not depend upon indices(d) Bounding faces can be easily foundThis question was addressed to me in final exam.This intriguing question comes from FVM in division Finite Volume Methods of Computational Fluid Dynamics
Answer» The CORRECT option is (c) Element CONNECTIVITY does not depend upon indices For explanation: All the entities should be NAMED separately in an unstructured grid. There is no way to directly link the VARIOUS entities of an unstructured grid. THUS, local connectivity has to be defined explicitly.

58.	The cell-centred arrangements are disadvantageous when we have ___________(a) Non-conjunctional and non-orthogonal elements(b) Conjunctional and orthogonal elements(c) Unstructured and non-orthogonal elements(d) Structured and orthogonal elementsI had been asked this question during an interview.The above asked question is from Variable Arrangement in FVM in portion Finite Volume Methods of Computational Fluid Dynamics
Answer» The correct answer is (a) Non-conjunctional and non-orthogonal elements Easy explanation: The treatment of non-conjunctional elements and the manner the diffusion TERM is discretized for non-orthogonal grids are DISADVANTAGES of cell-centred ARRANGEMENTS. They cannot PRODUCE GOOD results in these cases.

59.	Which of these terms need a surface integral?(a) Diffusion and rate of change terms(b) Convection and source terms(c) Convection and diffusion terms(d) Diffusion and source termsI had been asked this question during an interview.This is a very interesting question from Finite Volume Method in portion Finite Volume Methods of Computational Fluid Dynamics
Answer» Right ANSWER is (c) Convection and DIFFUSION terms Explanation: The convection and diffusion terms have fluxes flowing along the SURFACES of the control VOLUME. So, they have to be integrated over the faces of the control volume. So, the convection and diffusion terms NEED a surface integral.

60.	The centroid of the polyhedron is ___________(a) the summation of the centroids of the pyramids(b) the arithmetic mean of the centroids of the pyramids(c) the weighted average of centroids of the pyramids(d) the Pythagorean mean of centroids of the pyramidsI have been asked this question in homework.This intriguing question originated from Types of FVM Elements topic in portion Finite Volume Methods of Computational Fluid Dynamics
Answer» The correct choice is (c) the weighted AVERAGE of CENTROIDS of the pyramids For explanation: The CENTROID of each of the sub-pyramids is CALCULATED. Their volumes are also calculated. The weighted average of these centroids is calculated by using the volumes as the WEIGHTS. This gives the centroid of the element.

61.	Gradient for an unstructured grid is calculated by ___________(a) looping over the nodes in the computational domain(b) looping over the elements in the computational domain(c) looping over the faces in the computational domain(d) looping over the gradients in the computational domainI have been asked this question by my college professor while I was bunking the class.The query is from FVM in portion Finite Volume Methods of Computational Fluid Dynamics
Answer» The CORRECT answer is (c) looping over the faces in the computational domain Easiest explanation: Computation of gradient for the OVERALL domain is more efficient than CALCULATING LOCALLY element by element. For this purpose, all the faces are LOOPED over and the gradients are updated.

62.	Which of these entities need the information to be explicitly stored?(a) Elements, faces, nodes and neighbours(b) Elements, faces and nodes(c) Elements, faces and neighbours(d) Elements, nodes and neighboursI have been asked this question in exam.The question is from FVM in portion Finite Volume Methods of Computational Fluid Dynamics
Answer» CORRECT choice is (a) Elements, faces, nodes and neighbours To explain: The DATA structure for an unstructured GRID should CONTAIN information about the elements, faces, nodes and in addition to these about the neighbouring elements also. As they are not properly ARRANGED, the neighbouring elements cannot be defined using indices.

63.	Each face of a hexahedron is __________(a) Cuboid(b) Cube(c) Triangle(d) QuadrilateralI have been asked this question during an internship interview.My enquiry is from Types of FVM Elements topic in division Finite Volume Methods of Computational Fluid Dynamics
Answer» CORRECT answer is (d) Quadrilateral To ELABORATE: A hexahedron is made up of six faces. Each of its faces MAY have the same DIMENSIONS or may not. In general, all hexahedrons will have faces in quadrilateral (FOUR edges) shape.

64.	For a regular structured grid, which of these statements is true?(a) Each interior cell is connected to the same number of neighbours(b) Each cell is connected to the same number of neighbours(c) Each boundary cell is connected to the same number of neighbours as an interior cell(d) Each direction has the same number of cellsI got this question during a job interview.Asked question is from FVM in chapter Finite Volume Methods of Computational Fluid Dynamics
Answer» CORRECT CHOICE is (a) Each interior cell is connected to the same number of neighbours Easiest explanation: The boundary cells will have less number of neighbours when COMPARED to the interior cells. As the statement telling “Each cell” INCLUDES the boundary cells also, it does not hold true. It is not necessary for the structured grids to have the same number of cells in every direction. So, the statement “Each interior cell is connected to the same number of neighbours” is only true.

65.	Cell-centred FVM is __________ accurate.(a) first-order(b) second-order(c) third-order(d) fourth-orderThis question was posed to me during an online exam.The doubt is from Variable Arrangement in FVM in division Finite Volume Methods of Computational Fluid Dynamics
Answer» The CORRECT answer is (B) second-order For explanation: Cell-centred arrangements have predefined elements and their CENTROIDS are the grid POINTS. Here, the elements are IDENTICAL to discretization elements and they are second-order accurate.

66.	Consider a 3-D problem. Non-overlapping elements can be created by joining __________(a) face-centroids and edge-centroids(b) cell-centroids and edge -centroids(c) cell-centroids, face-centroids and edge-centroids(d) cell-centroids and face-centroidsThis question was posed to me at a job interview.This interesting question is from Variable Arrangement in FVM in section Finite Volume Methods of Computational Fluid Dynamics
Answer» Right option is (C) cell-centroids, face-centroids and edge-centroids Explanation: To overcome the PROBLEM of overlapping elements, in two-dimensional problem, the cell-centroids and the face-centroids are CONNECTED. Extending this to a three-dimensional problem, cell-centroids, face-centroids and edge-centroids are connected. THEREFORE, ENSURING that the connecting lines do not overlap.